Most Alt are worth zero because team are not updating those coins and are not interested anymore after launch
In addition, investors only have so much money to buy these coins with, and there are so many choices. In other words, the market is saturated, interest is probably waning, and most of these projects are turning out to either be scams or to be unnecessary.
The coins aren't exactly worth zero yet, but my best guess is that this is where most are heading. Best to sell these questionable tokens as soon as they're acquired and get bitcoin, which
isn't heading toward zero. There are some coins with decent value, like ETH, but those are more the exception than the rule in crypto.