I believe if as long as they earn profit, it doesn't matter in what coins they invested (e.g shitcoin, or legit coin). Actually shitcoin is altcoin itself, the difference only in shitcoin the token looks like dead (very low volume and got pump suddenly), while in altcoin, you will see how their price keep growing from time to time.
Investing in shitcoin is a big risk since like you said, it looks dead, however some people are still buying as it happen in the past that shitcoins also pump.
Maybe they think they can spend a spare of $100 usd in a shitcoin and if that grow x10, that would be instant money, they'll never loss the value since it's already been dump many times and as long as there's a volume, there's a chance buyers might notice this one in the future.