Beaker, like many classic characters, gets the brunt of the punnishment of all the characters on the show. No one knows just why he keeps coming back, and not just quit.
Of course, I actually had times when I wanted to quit. I wanted to quit school (and even my life) when I was constently harassed. I wanted to quit college when I got a "D" in a subject first year. But I'll tell you one thing, life is tough! You have to go through many painful indignaties to get to where you want to go. You want a good career? You have to pay big bucks, and study hard, not to mention how many times you strike out, to get any where.
You see, the reason I think Beaker puts up with all this is to get his dream job as a scientist, and the only way is to be the assistant to Honeydew for a while. He's like Charlie Brown, Wile E. Cayote, and Dilbert. He keeps plugging away and he doesn't care about all the failures, painful injuries, and odd growths he'll eventually get. He's a hard worker, and I for one salute Beaker on his nobel quest!