Is their any realistic weight to Trump and Rudy's threats to invalidate votes and get the Supreme Court to intervene in the results, or are they just throwing a tantrum?

Bother to elaborate? I thought Trump had lowered tarriffs

Tantrum. The lawsuits he's filed have mainly been shut down, and he has no cogent legal argument. Pretty much all states followed their legislature's guidance for mail in voting. 

Based on the evidence presented, which has been none, it's hard to see a cogent legal argument for fraud. 

At best, Trump can make some procedural arguments. Some states changed voting policies due to covid without going through the full legislative process. But even if Trump were to prevail in these lawsuits.

a) it wouldn't be nearly enough to get him ahead in any state, let alone in Pennsylvania, Georgia, and Wisconsin/Arizona which he'd need to win.

and

b) the courts are VERY reluctant to invalidate votes. If Trump won, they'd probably say something like "this was procedurally illegal and must be changed for future elections".

Unless Trump's been withholding some actual good evidence, this is not going anywhere.

Trump CAN get a recount in certain states (Wisconsin if he pays for it, Georgia, and possibly PA, but not likely if the margin expands), but recounts almost never change things by more than a few hundred votes, if at all. So, that's also a dead end.

He lowered taxes, for some, not tariffs.

Tariffs are taxes specifically on import. So, for instance if you want to buy products from China, you may have to pay 30% extra. 

A lot of people in America think China pays the extra, but it's us who do.

As for the Dow rising, I think it's mostly because they want to see a stimulus bill. If Trump was smart (which he's really not) he'll try and get it done before he leaves office, to rob Biden of a victory.  

My deepest condolences to the american people. You tried but failed. Well, let's prepare for a new dark chapter in Human history.

They atleast likely have someone decent to communicate with now,even with the memes about his sentences.

The next dark chapter in Human history will be full blown irreversible climate change, not just the American people but for everyone, not sure Biden is up for the challenge, Tump definitely wasn't :/  

Biden has been talking about the dangers of climate change since 1988 or before.
His policy hasnt changed on the matter, and he knows something has to be done about it, and that it was a mistake to pull out of the Paris climate agreement (the entire world, basically came together on). He know frakking oil is a huge issue (sink holes, earth quakes, polutes ground water, ect ect).

Unlike Trump (who basically didnt care anything, how much industry pollutes), hes a huge improvement.

Man, the amount of shit from both sides... Listen up, y'all! It's NOT the end of the world and it wouldn't have been if Donald Trump had won either. 

It's bad for the future of socially conscious state policy beyond identity politics, but it's hardly all that crap. 

Oh brother...  

At this rate, you'll be getting schooled in democracy from Britain of all countries! 

You, stop with this moderate common sense bullshit, we dont like that folks try to be moderate round here

I absolutely do not understand your issue.

If one party is popular enough to secure a win over a long period of time then that is exactly how democracy is supposed to work. As long as those victories are not the result of fascism or dictatorship they are perfectly fine. I know the Americans are used to a constant change of leadership but that's not the norm, nor is it supposed to be.

In Germany we have had the same leading party for the past 15 years and the same party is currently still leading even though much weaker than it was before. It's what the people wanted and it is fine. We might not have a 2 party system but we have it de-facto since the 2 leading parties have been at the forefront of politics since WW2 and they still are the 2 most voted ones vying for wins. At some point our long leading party will lose because when the landscape changes voters will sway. It's a slow process but it will happen eventually. It will happen the same in the US if they ever abandon the EC. There is absolutely nothing wrong with one party leading for 16 or 20 or 50 years. That just means the majority of the country is happy with how things are going. It rarely happens because things change and parties are lead by humans, but it's a good sign.

As time goes on 3rd parties will strengthen and we will see the need for the leading party to create coalitions, weakening their position. People in the US are obviously yearning to vote for 3rd parties and as soon as EC is abolished you will see a massive surge for them. Hell, it might even end up as a big win for Republicans because they can score a coalition with one of the bigger 3rd parties.

Again, that only applies to democracies, not authoritarian dictatorships.