He won't be an all-star player, but the cap will steadily rise and $30M will be the new $20M in a few years. It's supposed to go to $154M next summer and then to 170, 187, 205 over the duration of Devin's contract.
If he becomes a steady 22/4/4 scorer on good efficency and a solid defender, his contract will be fair value...if he can stay healthy. And will be easily tradeable for an actual star if needed.

This is the shot chart from that game.
He took so many threes because he got hot.
Just one attempt (miss) in the restricted area and 0 FTs isn't how he should play.
He played like that because he just came back from injury, but we need him to get to the rim, draw fouls and collapse the defense more.
We wrote about it over the past week, the biggest issue with our offense isn't that we go cold from 3pt line, that happens to every team, but that we have just a couple of players who can consistently attack the paint and because of it our offense is really easy to stop if 3pts aren't falling.