I made similar mistakes too, I bought some altcoins years ago believing that they would be the next Bitcoin and they failed, maybe 2 out of 10 did very well, I could have made a lot more if I bought Bitcoin instead.
Later I found out that the problem was me, I couldn't tell the difference which coin are better for my money, so I ended up picking many bad projects, but instead of walking away I startesd learning how, today i have somw Bitcoin and lots of altcoins too, i am now better at picking them.
Bitcoin is the best investment for newbies because there isn't a lot to learn about Bitcoin, all a newbie needs is a trusted Bitcoin wallet and the right place to buy the Bitcoin, it won't take very long for newbies to decide if they are going to own Bitcoin or not, it is less complicated to understand, but it is not the same with altcoins.