At a distance it actually doesn't look too bad but play with it for a bit and see what happens.

I'm not a professional painter however did you prime before applying paint? It may say "no priming required" but in my experience you probably should prime nonetheless as it helps with the adhesion, as well as sanding with 200 grit sandpaper, just don't go too fine or you'll end up not giving a textured surface for the paint to adhere to.

What you should really do is, prime, put 2 or 3 light coats of paint with 24 hours between each coat (so it completely dries, not just dry to the touch like it says on the can) and a clearcoat (matte).

all I can say is dont use 100grit and a belt sander.....
it turns out bad

Haha ...... that's funny.

completely dry = some brands 3 days before you can put a clearcoat.

read the labels. thats your best friend.

Edit : And i mean both labels, sometimes the paint label will say its dry after 24h, but the clearcoat label will say you should wait a couple of days after it dries to let it cure fully before clearcoating.