What stakes is this? and how long were you playing with MP for? He's most likely just a maniac. I don't understand the point of a colluder showing down their junk hands

Today i sat at a 2/4 table with someone similar. If he entered the pot he was constantly raising, no matter what he had. It took a few hands for people to figure out what he was doing. (everyone folded the first few times, and the ones that went to showdown he just happened to have big hands) Some other 2+2er and I busted him out of his 250 stack in like 30 minutes capping hands like middle pair and top pair no kicker, and calling down with ace high. The pots were always 15BB or more. He busted and went to 3/6, I followed, he went on a hot streak then almost busted again and left. I found him at 5/10, a stake i never play but decided to sit with this guy. Unfortunately he caught a big hand against me and I ended up 100 dollars down on him and a little sour I didn't have a bankroll for 5/10. I don't think this is collusion, and Stellar makes a good point on the development of the hand. I think it's just a donk, an overplayed AA(unless the CO knew MP) and a crying call from the kings.