haven't traded in since the ps2 era, about 80+ PS2 Games, 70 DS games, 15 3DS, 1 Vita, 7 PS4, 10 Wii U 50 PS3, 35 WII, 50 360, and possibly some gamecube and xbox games.  

I would GIVE it to a friend but not trade it to a store (for the same reason)

...but when I am done with a console it is often way over the time when someone would be interested in an old console.

I have, with great joy from both giver and receiver, given away old handhelds when they were past their prime.

Was well over 2,000 games ,now about 800 not including digital , I used to be a keeper but when the PS3 game out it was $900.00 here in Australia , so I traded in a lot of games to buy it and a few new titles , and have done so with every new console since then , one of the reasons being with new hardware they have a higher minimum trade in price , drop their restrictions on what games they'll take, and with different bonus schemes I gain a 30% discount ,so
I end up with a new console and a couple of games and get rid of all my lesser games whilst keeping the gems.

I got rid of the majority of my 360 games because they were taking up too much space. Had over 100, reduced it down to like 30 of my favorites I still keep.

For Xbox One, PS4, and Wii U, I'll keep pretty much everything I have until 9th gen starts. 

I have a good job and don't need the extra money. I take pride in keeping this industry on its feet. I'm a great patron of this day.

I even bought gta 5 three times and many others twice. Retail first and then digital a few years later.

I like looking at my collection. I DID just give away almost all of my PS2 games this week, though. I went to the barbershop and some kids were playing DBZ Tenchaici or something. We got into a big gaming discussion and I thought to myself "Hmm.. I don't even have a working PS2 anymore and I have all of these games. I won't miss them."

Pretty proud of myself for that one.

I have about somewhere in the realm of 800+.

Firstly I am a collector, through and through

Secondly I am very shrewd with my money. If by trading in a game I get back maybe 20% of what I paid I see that as a redundant financial transaction.
.....In saying that I very rarely buy games for full RRP.

I like collecting things, and I've found I deeply regret selling my old games and consoles. Haven't done so in nearly 10 years.

They are my precious.

I've no idea how many games are in my collection. I don't trade in unless I'm upgrading to a better version (a truly better version) or I really don't like a game any longer. The few times I've traded in a game because "I'm never gonna touch it again" I regreted it later.