Would I make good money running a cake business on the side?

You can't make them at home, you have to use a commercial kitchen for anything being sold as food to customers.

As long as not to many people are putting in more effort and commitment than you at making cake in your area. It's only fair for the more committed people to get the most clients. Either become really good at making a very tasty cake or selling a regular cake.

No, to own a bakery is a full time business the overhead would kill you doing it on the side. Figure out your budget for the rent and equipment you would need and packaging and accounting system and you will see it isn't on the side. Most bakeries sell more than cakes because cakes don't sell for enough to make a living unless you are doing some major cakes that you can sell for thousands.

depends on where you live, how much you can afford to advertise, how many bakeries are in the area, etc.