Profitable/unprofitable is the wrong way of looking at it, because it implicitly ignores opportunity costs. Putting your money in a savings account at a big bank might be "profitable" in the sense you're getting paid some meager interest rate (eg. 0.1%), but it's definitely not the best option, like a money market fund or equity ETF. What OP probably meant was that slavery was worse than the alternatives, like putting your money in a savings account with meager interest rate.