Personally, I don't have any experience in bitcoin base investment websites who give high profits or which is commonly known as hyip (high yield investment program) sites. But I know someone who does. He is really into these sites and have made a pretty decent income and he's been encouraging me to try it but I refused countless times. I've seen these kind of sites and most of them are ponzi and scams. They will pay you on the first few weeks but after a while the site will be no longer active and they already got your money/btc. Some are lucky enough who profited a good amount especially if they registered during the first week the site has been running but unfortunately to those who were invited by the pioneers when the site has been up for almost a month most probably they will lose their money because some of those sites have lifespan. Once they get more BTC to split among themselves you're gonna kiss your coins goodbye.