Firstly, it was "low to medium" risk, not "low" risk.
Secondly, pretty much any reputable ETF (or combination of ETF's) can quite easily achieve this over 30 years.
Secondly, pretty much any reputable ETF (or combination of ETF's) can quite easily achieve this over 30 years.
Vangaurd is predicting low growth of 3-4% over the next decade.
Vanguard's predictions of 3-4% over the next decade mean that if you do a straight dollar calculation you'd be closer to ~7%, because that 3-4% number includes inflation, once again.
Be advised that they are not designed to be held over more than a day, although with the current bull market, they have not actually been hit by the decay factor inherent to all leveraged ETFs.
Other higher-risk ETFs would be things like solar/wind sector ETFs (e.g. TAN, FAN, PBW, IQCLN, QCLN, etc.) or bleeding-edge biotech (e.g. SBIO).
I'm sure there's SOME ETF that managed to do 15% returns over a 30 yr period, but that's just selection bias after the fact. It doesn't mean that ETF would do well this year, or next.