Obviously!
If you have only two types of ice cream in the shop customers will for sure buy more of those brands than if you would have 100 different types.
The moment there are multiple coins in which to invest even if the majority would keep most of their investment tied to bitcoin they will still spend a few $ here and there on altcoins, so cutting down that supply would for sure drive more money into BTC

And there s another thing, some choose to invest in other tokens because they know that if they are lucky they will hit the jackpot, there is no way for BTC to get the same return as some of these tokens, for example, Shiba Inu went 46,000,000% in 2021, so some are thinking of selecting 100 coins, putting 1$ in one and if just one does the same they will earn far more than they could earn from BTC. At the same time, they could earn -100  , but that's another story. If those opportunities would not be there the 100$ would go to BTC or at least a part of it.