1) Most of us are incredibly underpaid
2) A common question is when asking how candidates prepared that resulted in offers is "How many problems did you do on leetcode?" I'd never heard of leetcode but it seems if you want an offer from FANG, Uber, Lyft, etc then you put your time in practicing programming problems.
1) By what metric? Also, who's we? I am a full-stack engineer and feel properly compensated if not over-payed given my expectations.
2) Leetcode has been extremely helpful. Not just in interviewing, but also in understanding how to have more granular control of space/performance. However, it is not the whole picture and I would point people to the famous coding university github: https://github.com/jwasham/coding-interview-university and further push people to follow research and coders they admire such as Peter Norvig: http://norvig.com/
To go from 100k to 200k seems like it would take years unless you jump to one of the FANG companies