Considering the scenario you have in mind, Mr. Bob is the most wise investor, because he is investing on the most trusted and reputable crypto of the market, which is determining for another cryptocurrencies to go upside and down.

The other two investors commited some mistakes. The second is putting too much funds in altcoins (50%). It means 5000$ from 10,000$ and we don't even know which altcoins she picked. She may compromise her investment considerably if choosing a scammy pump and dump altcoin or memecoin.

The third investor shouldn't do DCA near a bull run, having 10,000$ ready to be invested. He is depreciating his money's potential this way. DCA is recommendable when you don't have a large budget to invest immediately, so you have to rely on monthly income from your wage or another investments to purchase BTC in small portions.