There is a lot of shilling lately (again) with "the flippening" event happening. Ethereum has created a new market which is basically 99% scam tokens, rugpulls, pump and dumps and NFTs which are probably used for money laundering. Anyway, the thing is, there is definitely if a demand for all of that, even if it's all based on a platform that's not decentralized.
So to the point: Would you quit if a centralized shitcoin managed to surpass Bitcoin in marketcap? At that point it would be clear that entire space is a joke. Bitcoin would still march on as usual, but it would be just sad to see people putting their money on shitcoins rather than on the only actually decentralized blockchain worth anything.
I guess that could happen, mate. In fact, at some point, I do believe that bitcoin will be surpassed. Bitcoin is kind of limited when it comes to use cases, so that may be a killer. I only see its usefulness as a Store of value, hence with some other altcoins, we can find a wide variety of use cases. That said, I don't think that the space would become a joke at that point as the "shitcoin" that surpasses Bitcoin may be the recipe that solves the basics problems of scalability and security.