And a few years ago Litecoin was #2. And a few years from now some other coin may be #2. Can you guess which one? You can't. It might not even exist yet. The point is, everyone hopes to be holding the next Ethereum but the fact is - most are not.
Although we disagree, I do get where you are coming from. There are certainly some alts that are more or less doomed ... forever sinking. And yeah, many of their holders probably would be better of selling into fiat or btc.
However, the same way we can't say what coin will be #2 years from now, we can't even say where most alts will be even 1-3 months from now. Sure, perhaps btc dominance increases, every alt flounders, and folks will wish they have sold. Or btc crumbles back to 6K, alts have a run, and we are kicking ourselves for selling our alts at their bottom when if we waited a month we could have gained 2-3x as much.
It works both ways. Most (or I should say many) here aren't just holding a fortune in junk alts hoping 2 years from now it turns into ETH. Many trade the swings, many hold but have no reservations about selling at the right price... and many realize they have no clue where the crypto market will lead.
You are also overlooking risk/reward. If someone puts $100-1000 into some dinky alt hoping it'll turn into ETH years from now, so what? That's a risk they feel worthwhile and isn't so much as to really hurt their finances... yes, most likely they will lose, but if they win, they win big. So who is to tell them they are wrong?
And I'm sure you have noticed BTC isn't exactly doing great lately either. Folks selling into fiat would have been the better move, not into BTC ... but as I stated, nobody really knows where prices will go.
I'll also state you may not even be wrong, perhaps every alt holder should sell into btc -- nobody can say. I just dislike it when folks post here acting like they are some expert and know for a fact where markets will lead. It's up to each person to weigh their own risks and decide for themselves.