Let me tell you something about the startup thing:
I have had my fare share with building a startup. I left my job to work on my (in development) startup.
I worked for a year, faced some financial problems, no traction in the startup product after laughing beta. I concluded that the product is not market fit + I targeted wrong group of customers.
Now, I have joined a corporate job again. At the moment, it seems okiesh work pressure but not sure how it's gonna go in future.
If I do get some decent free time, I will start building another startup.
From my previous mistake: I will only leave a corporate job If I start generating revenue that is greater than 70% of my salary.
Now coming back to your situation:
Are you generating revenue? If yes, is that more than enough to sustain your life (+ dependents life) without any financial issues?
If no, it's a risk and you need to calculate it.
Now you mentioned, you already have a job. Which is great. So you got a revenue source.
So I think for you, the question you should be asking is to yourself whether you think your startup will work or not.
How much confidence do you have on your startup?
Do you think it's gonna work? Or it's just gonna fail like 99% of other startups.
Is it bigger than working at and having google in your resume?