How can I make $50k in 4 months?

I suppose the easiest is to find a job that pays 150k/year.

But more seriously, you could flip houses if you have enough capital or access to it. This is not surefire at all, though.

somewhat similar from two weeks ago "Ask HN: How to make an extra $50k+ per year without changing jobs?" https://news.ycombinator.com/item?id=30322965