I think if you move to an area of high salaries (and, usually, high cost of living), such as Silicon Valley, Manhattan, Seattle, or some European job markets (e.g. Zurich), you probably can achieve a mid-career salary/compensation of $200K or so (significantly more if you are good, or went to a prestigious school, but I think $200K is eventually achievable for any decent engineer). Alternatively, you can create your own online application, which will be in very high demand, and will not have good analogues. You can also consider opening your own SaaS company as https://audext.com/.