Jupiter’s mass is 1/1047 that of the sun. If it were 100,000 times more massive it would be 100 times more massive than the sun, and would be a super giant star.
In order to be a star, to fuse hydrogen into helium, requires enormous pressure and heat. Fusion only occurs at the very center of the sun, heat is transferred by convection to the surface and radiated away. The specific power generation of the sun is about the same as a bale of rotting hay, about one half watt per cubic meter. The sun just does it longer - for billions of years - and with a lot more cubic meters.
I know how it works. The data I read say’s Jupiter would need to much more massive then it is now. I read one estimate that say a million times buts that’s clearly incorrect.