if you had been in the market for the last ten years with SP500 you would be up something like 150% of your initial investment, even with the latest drops. You would be very upset about the latest drop, but you would still be happy with your choice.

EDIT: saw your other reply: sadly many investment funds are just not worth it, it's not your fault, banks and similar are often incentivized to sell you a fund which has high fees and generally trails the market, the best choice is to invest in low cost index-tracking funds, but this is not obvious knowledge.