I do cybersecurity consulting. Specifically, Web Application Security which I charge $350/hr for and make about $300k/yr from this.
I am usually brought in when a competitor gets hacked and the company gets scared or as part of a high quality penetration test.
My experience is mixed between cyber security and fullstack development. This led to me having a very deep knowledge of how to properly consult companies regarding potential vulnerabilities.
High-performance distributed systems for capital markets. Basically started in capital markets and sought out to work on the most business-critical applications, acquiring skills along the way.
I have 10+ YoE, and I'm currently working in ML at Big Tech. I regularly get contacted by recruiters offering 100+ $/hr contracts unsolicited. I'm pretty sure those are bottom of the barrel rates and I would be able to get much better rates if I was actively looking.
250k a year in the current market doesn't sound like a lot.