2x? Try 10x
3x-5x is more reasonable.
But those numbers are before RSU appreciation, which I suspect you're massively underestimating.
FB granted 5 years ago went from 128 to 326. AMZN 800 to 3200. AAPL 29 to 171. GOOG 800 to 2700. MSFT 62 to 311. (Netflix excluded for the obvious reason.)
So if your total comp is 500K and half or more of that is long-dated stock (or you just didn't sell) then over the last 4-5 years you could very well have been making million a year or so. And 500K is doable for an asst prof.
Not guaranteed, of course. But cash is comp is risky as well. How many professors got a 7% raise to adjust for inflation last year?
10x pre-appreciation is certainly possible after 5-10 years in industry, though. Probably not the norm, but not some crazy impossible out-of-reach number.
Regarding IP: Yup. It's true. If you're willing and able to do the work to make millions in ARR from your IP then academia can break even. (beware tech transfer... universities can be more predatory than the slimiest of VC firms!)
Even at tippy top R1s that's a tiny fraction of faculty and requires a ton of extra work. But, yeah, it's a good case where academia can make sense.