This sounds exactly like my buddy from work- he invested super late in 2017 and then threw more in during the ATH. HE GOT REKT!!! Dude is down like $3,500 this year on a $6,000 investment and he keeps making really bad investing mistakes.
His biggest and most egregious mistake is he keeps going "all-in" on just a single coin trying to ride a quick pump. To him it's just like gambling and he gets a rush out of it. I told him he needs to stop being an emotional trader because he is trading based on nothing more than his feelings.
He also buys into the hype and loses all confidence on the dips- literally the exact opposite of what you SHOULD be doing.... *facepalm