I cannot take any GPL code and put it into a product and sell the product without releasing the source. As the source would have to be available, people could

I cannot take any GPL code and put it into a product and sell the product without releasing the source. As the source would have to be available, people could take the source and compile the software and then wouldn't have to pay me, so I could never make a profit. It's why GPL and LGPL code is best (totally?) avoided in commercial closed-source products.