basically yes
deep down I believe that any acitvity that results in profit without generating actual value (goods or services) should not exist and is unethical, but that's utopical.
it's free market, you will get burned many times, and you don't know if you are burning someone else or not, maybe price goes even higher and your actions didn't directly burn anyone. If you dump, the buyer knew his risks. If you are assuming the risks, it's ok to make money from it (or so goes capitalism). Go free trade! go libertarianism! go liberalism! we have the liberty and freedom to burn each other while richs get richer! yay!
buy many POS IPOs, you'll loose in some, win in others, and develop a sense of smell of what to buy and when to sell
Bitcoin started without any actual value. You can still argue it has no value today.
Free market itself works in a mysterious way which I doubt any of us mortal truly understand.