That's simply gambling. Might as well just use a gambling site and see your luck instead of waiting for months before you ROI in a HYIP site. The admin will run away, that's guaranteed. Some would even run away before the first investors ever get their ROI. There are some HYIPs that are outright scam. They let you deposit money but never let you withdraw your earnings or have very high minimum cash out amount.
Just how little you know of this world if you think that HYIP is good enough and you only have to get out before the admin runs away? There are tons of investment types like going back to school, franchising a business, creating your own product, thinking of a business idea and then selling it, establishing your own business, making a youtube channel, etc. There's a spectrum of investment opportunities out there and investment sites are the worst ones.