Know people who bought into a very rough neighborhood in the late ‘60s for around $20,000. They knew it would be rough, but the improvement was moving in that direction. Several break-ins, muggings, etc. later, houses in that block now sell for $1 million.
This is 100% happening in the Bay Area. If you bought in the Mission or in Potrero Hill in the 90’s you would be sitting pretty right now.