Westbrook is on a mission to get his first championship, which is why he's joining a strong team for a higher chance. I wouldn’t say he's "fortunate" that teams still sign him, because even if he were to stop playing basketball, he'd be fine, he's earned an estimated $200 million in his NBA career by 2023. At 34 years old, he's only a year younger than Curry, so he's not exactly "old."
The hype around Westbrook mainly comes from his OKC days, where he called the shots and could easily rack up triple-doubles. But when he joined teams with other superstars and different systems, he had to adapt, which made it harder for him to put up those kinds of numbers. The key with Westbrook now is the energy and intensity he brings to the court, rather than his shooting, which has always been inconsistent, especially from long range.
The problem with players like Westbrook is that he used to play with his fierce athleticism and this made him amazing, he used to get inside for scoring, pass very well, rebound.
Now he doesn't have that, dude is older and he can't shot for anything, so there is really nothing he brings to a team aside from maybe leadership because he has been around for long enough, but he doesn't seem to have a character that oozes leadership neither.
He is not "old" in the sense that he should retire, but he is old for his old style of basketball, at 34 years old, you can't dunk over everybody, Curry can still shoot, shooting has no age, curry can shoot when he is 40 too, there is no need for him to change his style as he gets older, but when you are 34, you are not going to be faster than everyone else. So, the "old" talk comes from that.
All the greats of basketball, MJ, Kobe, Lebron, they all changed their styles compared to their old selves, just look at their shooting vs their dunking every year, you will see that they started to shoot more as they got older and this means Westbrook has to as well, which he tries sometimes but as we all know he fails and misses most of his shots, which makes him not good at all.