After the SCOTUS shut down his previous attempt, he had another one ready to go. He's doing what he can with what he has at his disposal to do something that progressives have been clamoring for.

If the court strikes this one down, they demonstrate yet again that they are corrupt and illegitimate, and make a more compelling case for expanding the court, and if Biden is smart, he'll just take the next contingency plan off the top of the stack and announce student loan forgiveness again. He can be seen directly fighting against a corrupt conservative institution that is ignoring long established norms, in favor of a demographic that is apathetic because they don't think anyone is fighting for them. If the court lets it stand, Biden gets an accomplishment to run on, and students get relief and a big ol' demonstration that yes, Democrats are actually interested in making their lives better after all.

And the best part is, his own party can't stand in his way. Manchin can't do shit. There's no bill to split into "the bill we pass" and "the bill we kill because it might help people."

Biden is working in direct unobstructed opposition to conservatives here. He's actually persevering instead of giving up forever at the first setback like we've come to expect from Democrats (see minimum wage and the public option). This should be encouraged. This is something the party can sell to its voters instead of just scolding them to take their ineffective medicine.

There are a lot of people who are invested in the collapse of the system for their, their benefactors, or their "teams" benefit.. Who actively want to poo poo and block anything, under the failure of an argument of "Well it doesnt solve EVERYTHING and isnt PERFECT, so theres no point in doing a stop gap solution!"

Because they'd rather no one get anything, than someone other than them get something

It's not enough, but it's at least something