Client proposed a deal to me secretly ,please help me decide what to do .

So I am working in a small service based startup as a Backend developer from last 1.5 yrs, I was working for a US based client ( from beginning to still ongoing). So recently he called me and personally asked me what i was getting paid here.i told 16. (and got shocked that you are not even getting 30% of what i am paying to company).

He proposed me that he want to end contract with Company this month but asked me to freelance with him ( atleast 25-40 hrs/week). on hourly 15USD/Hour. He also told that you can make 20-24 lakhs in next 10-12 months. that is very good money.He said you can continue with current job and do parttime or you can quit and do fulltime freelancing.

i dont want to quit my current job as indian employers dont care about freelancing and it will create gap in my resume and it will affect my career.

I feel its good to work part-time atleast 25hrs parallely and make some side money, but he warned me to not disclose to anyone in the company .

I asked to one of my ex-colleague, they said it is very risky if company came to know about it . Company can terminate you and it will be very red flag for new employers and getting a new job will be difficult.

Please enlighten what should i do here?