Their was a time, when the interest paid by your savings account was +10%. Will it ever see those levels again? I can't answer that. You can accumulate wealth extremely quickly with those kind of rates.

Imagine, your investments being 'adjusted' by a market correction. Lets say, you lost $10K. How long, at 3% or 4% would it take to recoup that loss, without additional investment. Basically, you can't, at least not in your lifetime. Those corrections happen, and your losses, after a while will be greater than $10K. Big fishy has to eat.