No, I don't think so, I would rather say that altcoins have helped the adoption level of Bitcoin greatly because if there were no altcoins at all, it would take more time for Bitcoin to spread around and it is altcoins that make Bitcoin look better because people compare altcoins with each other and also with Bitcoin, and when they find out which one is the best, which is Bitcoin, of course, they become more interested in Bitcoin after that.
That's just your thought, the reality it's the other way around.
If they know Bitcoin, they invest it and they feel they didn't make a lot compared to altcoins, they will try to invest in altcoins.
If they now altcoins, they invest it, they will keep invest in altcoins because they like to flip their money.
People choose to invest in Bitcoin when they get scammed in altcoins or they listen to their so called financial advisor.