Profit isn’t illegal, so it’s not technically theft in any legal sense. But if a single individual (the owner) takes the fruit of an organizations labor and doesn’t distribute the entirety of that fruit to the workers (including themselves) and continual operation of the business, they are essentially stealing what is due to the business and workers. If the owner skimming off the top weren’t there, the workers would distribute the fruits equally, and ensure some is set aside for business costs.