I was in the same situation as yours 6 months back. I left my job and persuaded my desire to startup. Turns out it takes more than being great at coding to build a startup. I'd to learn Marketing, Pitching, Emailing etc. skills in my journey which I never thought about before starting up whereas, I thought building a good product would cover that part. So, I'm not scaring you away from starting up but I'm just saying that you should consider these points as well in your decision making process.
I've gathered few questions and important points which I would ask/tell myself before starting up again. Here are they:
1) Do you have a co-founder which can leverage your skills?
2) Have you zero down on an idea and did your market research?
3) How confident are you about the target market?
4) Do you have a execution plan or Goto market strategy?
* Market first, product later
* Ideas are worthless unless they're executed really well.
Thanks,