You could certainly choose a few paths that are likely to pay higher salary that most of the scientific computing jobs you'd likely get. On the other hand, the pay for some of those scientific computing jobs is reasonable, and often the work is more interesting for someone with your background. It's worth bearing in mind that unless you are extremely unusual, you'll need a few years training in industry as well before you are really running on all cylinders.

You'll really have to think about your priorities, but it sounds like you have a bit of time to do that.

Probably the worst case is "support programmer for a research lab", some people do well there if they love the lab and the work but it tends to combine poor pay with extremely limited options for professional growth.

1) If you are a US-born citizen and qualify for a security clearance, jobs aren't as scarce as you think.

2) You are right the pay is worse in the public / government side. I will say - you might not believe me now, but it really is true that once you make enough money to pay all your bills, suddenly more money is less motivating than the ability to work on interesting problems.

What I just said above supposes that most lab work is interesting, which is not not the case, but I still think it's better than the average SWE's workload at your average tech company, just based on my personal experience having done both at different times in my career.