Are you sure? Lending is a pretty common "investment" out there, there is people doing some real money with it. "bullshit investment schemes"... besides pyramids (which are always a success -for their owners-), what about herbalife, omnilife and all those affiliate programs?, all those work with fiat.
How would you grow your bitcoin?, probably trading is also "dumb" for you, buying then selling is a risky activity as well, so, only people fearing risk is aware of the value of bitcoin according to you?, how do you handle your fiat?, is it under your mattress?
Much of my fiat lives in financial institutions that are insured and their operators are legally accountable if they decide to help themselves to it. If this was not the case then the money would not be in there.
People can lend fiat via established sites like Zopa that take credit ratings into account, ameliorate risk and use debt collection agencies, not one guy writing 'hey dude. I need minzerz luls. Here's my address' on here.
As for investments, if a guy with a bag over his head walked up to you in the street and asked for a bunch of dollars (cash of course) for a vague idea but no contact details or business plan or paperwork, would you hand it over? People do that on here every single day.
