Jalen Green just turned 23 years old, a full year younger than rookie Dalton Knecht. His contract is not for what he is, its for what he will be. Just perusing his peers, like Brown, Booker, Edwards, SGA, etc. Most of these guys had big leaps in age 23 season (which would be Jalen's next year), so to try to claim Green is a bad contract...is just odd. He didn't even get a max deal, he took less than max. Now, player options are always problematic, but this is hardly an albatross. Frankly its just about right for him. Its a "you have made great progress, but we are not fully convinced, lets stay the course, and the kick the can down the road a bit. We give you the player option, so if you keep improving, you can opt out and get a bigger deal since you enter the 30% max threshold, rather than the 25%". It's a good compromise that gives each party a carrot depending on how things go.
Jalen has certainly not shown he is in the highest tier of SGs, as you would hope, but he is nothing to scoff at, and he can still get there. He has improved across pretty much all metrics over this, and the prior 2 seasons. He hasn't even entered his prime, and there is no reason why he can't take additional steps forward in the next 3-4 years. His efficiency has improved across the board, while simultaneously seeing his free throw rate plummeting. Changing nothing else, and simply working on ways to draw fouls over the offseason, presents an easy path to continue making leaps.
He has also never been fortunate enough to play with a vertical spacer, or shot spacing big, which limits the room he has to work with going downhill. Outside of a short period last season, where Sengun was injured (And Green was awesome in this stretch), he has always played along side a paint clogger in Sengun. Furthermore, even the spacing from the non centers, has not been ideal. There are no deadeye shooters in the roster keeping help defenders honest. This is another easy opportunity, in tinkering roster construction, to empower Green and help make the game much much easier.
Now, while folks may try to paint him as a bad player, opposing coaches are not. They are treating him similar to the other premiere guards in the league.
Hell, lets just look at his last five games

Awesome in a blow out of San Antonio
Outplays Lillard in a close win over Milwaukee
Plays great in a loss to the Jazz
Outplays Ant in a good win over Minnesota
Very poor game in a loss to the Warriors.
You may think a 22 year old will not get significantly better, and take the under, that's completely fair. Its certainly possible he doesn't get better, and is the next mid tier Ingram or Barret, but history has shown us that is far from a finished book. Now I am not going to sit here and say you should value him, or you should trade for him, or whatever. But among the worst contracts in the league? Nah, not even close.