I would roundly disagree. If you find an unexploited niche and effectively corner it, there are still opportunities out there.

Just look at Bitwarden. It started out as a free and truly secure answer to password managers that were cross-platform and web/browser-based, but had issues with trust and privacy. A lone developer put his money where his mouth was, and built the product up into a SaaS that is now a small but profitable company. It’s now the fastest growing password manager out there, and certainly one of the more popular among techs.