Of course, lots of stocks don't pay dividends and people still trade them. The stock market has become somewhat speculative in practice that way. But the core concept is that the stock is a source of revenue for the person who owns it. You're literally sharing in the profits of the company.
Bitcoins are a completely different instrument. They can't/won't pay you dividends, so if you believe they have intrinsic value, you have to look elsewhere. A lot of people would say their intrinsic value is that they're liquid -- you can spend them to buy things.
So if you want to argue that buying GME stock and buying Bitcoin are both speculative activities for most people and that it's all essentially gambling, I would agree with you in practice. But the underlying concepts are very different.
Even a pathetic stock like GME has some "value" due to a manifestation of assets, income and growth/earnings potential. An yes, irrational beliefs and expectations can play a role in determining this "value" as well.
Bitcoin is nothing but electrons. It has no real world manifestation at all --- no assets, income or growth. It provides no real world function. It's value is derived purely from recursive speculation --- the idea that ever more people will come to speculate in the speculation thus perpetuating it and driving the speculated "value" ever higher.
As they used to say in school, it should be "intuitively obvious" that this game of musical chairs can't and won't continue forever. At some point, reality will intrude and all that will be left is a pathetic, non-functional excuse of a currency that almost no one uses to buy anything in the real world.
2) Someone had "rented" a lot of GME, sold them, and had to rebuy them before the expiration time of the "rent". So some people expected that they have to buy back the GME stock at a high price. (IIRC this window is over.) Nobody is forced to buy Bitcoins in the future at a high price.