I give this same advice a lot, and it's always telling to watch people's reaction. Human nature is all about defending what you're currently doing, against all evidence that there's a better way. So, yeah, it's impossible to get 5%? Are you sure about that? Over a 40-50 year period? You'd have to look pretty hard at old stock charts to find a spot where you could get overall returns that low. And yes, inflation exist…
Yeah, I've tried the whole stock market thing twice now. Put $1,000 in as a tracker against the market index, expected a decent return; of course, I put it in on Sep 10, 2001. Never got that money back. Thought I'd try again a couple of years ago, so I bought shares in Lloyds Group. On the eve of Lehman going south. Never got that money back, either. I think I'll stick to 3% savings accounts, thanks.
And a quick word to the wise: Never "invest" in individual stocks. That's speculation, and chances are most of the time you do it you'll lose. "Invest" in a fund that tracks the S&P 500, and don't even think about taking the money back out until you retire.