The top one is making $100k MRR in just 7 months → https://twitter.com/deadcoder0904/status/1398141109075730436...
One sold for ~$1m when it had $20k MRR in 8 months of launch → https://twitter.com/levelsio/status/1377095814963589125?lang...
Another smaller one sold for $4k with $100 MRR → https://twitter.com/heyyfernanda/status/1398679798281605120?...
There are many others getting funded because of GPT-3 → https://twitter.com/kearonis/status/1378832191413702663?lang...
So I'd suggest building it around GPT-3 as it's just a bunch of API calls. Make it profitable & sell it if it's a life-changing amount. The hype around GPT-3 is at an all-time high so big exits should be easy.
And if you want ideas, just copy one of the popular apps & offer it with a discount or make it 10x better → https://www.youtube.com/watch?v=opkHJLVAM4A
Read the Paul Graham essay on ideas → http://paulgraham.com/startupideas.html
You need to solve a real problem so you get paid by people. I have been at it for ~4 years with nothing to show for it so my suggestion is to fail fast.
I have hopefully figured out now how to make a SaaS successful so I should be good for now but you don't waste time. Start now. Fail fast. Use SaaS templates like Bedrock & Style it using Tailwind UI so you can focus on the core logic.