It is true, but today's richest people also had to work hard or to be very inventive to become rich. Bill Gates is a very talented person who created a big company and Windows is the most used operating system in the world. So he deserves it. It's not easy to do what Bill Gates did. The same is true for most self-made billionaires. They all achieved extraordinary things, or they were extremely talented in some area.
This is completely different from someone who simply buys bitcoin, and 5 years later, voila, he is a millionaire.
So now you are judging who deserves to have money and who don't? Nice. Do you know that Bill Gates pretty much stole the DOS OS that started his path to riches? Just sayin'...
It so happens that, without a reliable way to determine how much somebody contributed to society and how much benefits this society owes that person now, money was invented as a medium of exchanging work-hours for the benefits. The fact that some people now have most of it, shows that it is far from perfect, but that's all we have (until bitcoin).
So, when you invest money into something, you invest your work. If your work (in form of money) makes you richer, that means you were "very inventive" with where you applied the proceeds of your work to, instead of wasting it on hookers and whisky.
One last thing, don't forget that holding bitcoins is a very tough task in itself. You have to protect them from hackers, not sell them when tempted, not send them to mtgox, etc. Try holding 1btc for 5 years, just so you would have some first hand experience.