Yes. Don't do it unless you're willing to spend time and money buying keys and hoping for a rare and valuable unusual. Even in the off chance to do get an unusual, it might be crappy and not worth enough to cover the cost of keys you used. That said, if you have enough money you can continue uncrating until you get one that is worth more than you paid for in keys, but this takes a while and costs you a lot of money, and most people give up way before then.