All I see MS saying is that it will be profitable at some point. It isn't yet, and they're over delivering on value for customer and publishers for content acquisition. So no, they're not lying, they're also not saying it's profitable or sustainable the way it currently is.

All I can find is this
https://www.videogameschronicle.com/news/xbox-says-game-pass-subscribers-spend-20-more-overall/

20% more, that's trending below the extra time and money spend on entertainment due to the pandemic.
https://www.npd.com/wps/portal/npd/us/news/press-releases/2020/across-all-age-groups-us-consumers-are-investing-more-of-their-entertainment-participation/ with total time spent gaming increasing 26% and total spend increasing 33%

And should we be happy DLC and MTX will be the driving force behind subscriptions, holding content back to sell separately in pieces wasn't that scoffed on not long ago?

I don´t like the ... as a service model at all. I like to own as much as I can. That goes from books, to music to games. The only subscription I have is Disney+ and that´s because I´m in a sharing arrangement with my dad so I can use his Netflix.
I can understand it´s a model that might work well for a certain type of gamers, but I´m not one of them.
I also don´t buy that many games and most games I buy now are discounted or secondhand. Getting a subscription would cost me more.

Sarah Bond was talking about their GP data recently, and said that GP subscribers, among other things, spend on average 20% more on their platform than non GP subs. 

As for whether or not we should be happy about DLC and MTX being a driving force of revenue behind subscriptions...everyone has to answer that for themselves. Personally, I'm totally fine with paying for good DLC content, less so for MTX, but I also don't care about their presence as long as they're not too intrusive. The other factor for increased spending habits though would be that people may play a game from a franchise (or developler) they weren't previously familiar with, like it, and then end up purchasing a new game in that series (or from said dev) when it launches outside of the subscription. It's not really that hard to see how there could be an increase in spending habits for people, while still being a good deal for them.

This is pretty much my experience, adding in that I also replay games I've beaten all the time at random intervals and play a bunch of games with seemingly infinite replay value so it affects how I finish other games in my backlog as well. Feeling like there's an expiration date to the games on a service puts a weird pressure on me to either never start them because they might not be there when I get around to wanting to finish them, or rushing through and feeling like I didn't get to really play the way I wanted to.

I play like a handful of games a year, game pass is zero value for me. Generally I hate subs, subbed to absolutely nothing.

I don't have much interest in the subs and actually think the type of games best suited for this type of service isn't what I want from gaming.

"GP saves me so much money in buying games that I end up expending more money buying games"... yes both don't add up.

The idea is that since you are not having to spend 60-70 dollars per game, some people (not me necessarily) will be more willing to buy DLC packs and micro transactions because of that fact.  Since gamepass is giving those people 400+ games to potentially spend across, it is possible that the overall investment on DLC among several games will add up to spending more overall than they would have if they had to buy each game individually while ignoring DLC.

It has nothing to do with the value of the service or how much you save, but more to do with the spending habbits and mentality of the gamer in question.  It adds up just fine.

Neither me nor SvennoJ was disputing any value of the GP.

But you can't at the same time say how great GP is for you on saving money with games but then you end up expending more than before (and well if we look at TV subs that is almost what is happening when people end up having several subs where before they possibly didn't even expend anything or moved from cable to stream to save money and now it reversed).

So again, if you end up expending more than before then GP isn't saving you money it only gives you the ilusion of saving or you can say that you are playing more games or more time and them when you dilute that you are paying less per minute of play. But you can't say GP saved you money if you are expending more because of MTX, DLC, etc (because that is the grand plan and why games have been sliced and diced since the introduction of internet updates to console gaming, and well the main reason I don't like the idea of gaming subs is exactly the one that the model is more sustainable on game as a service, mtx, dlc and other stuff that prevent a delivery of a full product day one).

See you are ignoring the Value.  If you truly want to compare what you are saving, while also spending more on DLC than you normally would have, you need to compare the price of all those games plus the DLC to what you are paying for the DLC plus a subscription.  The difference is staggering and most people would never pay that much.

So while you may be spending more than you normally would have on DLC across more games, you are still saving on the base cost of those games.  Most people will not have bothered with buying every game let alone the DLC on top of it.  It really is a simple concept.