Can a person assume that, if given enough time, risky investments will be worth more than safe ones?

Is it a fact, or at least reasonable to assume, that if given a few decades risky investments(say perhaps around 35% chance to lose all value) will be more profitable than very secure investments? Does compounding on productive years erase the losses from previous years, or will small rate of return compounded have a higher probabilty of being more profitable?

No, you can't assume that, since risky investments can go to zero value. But you do have a reasonable chance at a higher gain, especially if you diversify enough so you don't have all your eggs in one basket that could turn out to be another Enron. How many different risky investments you'd have to have to diversify enough to be reasonably safe depends on how risky the investments are.

a few decades???? that's alot of time... atari was once a risky investment, and people made millions off of it, that sold it in time... however if you had bought atari stock in the 70s and held on to it "for a few decades" then it would be worth absolutely nothing now... risky investments mean having a watchful eye on what you invest in and knowing the market, otherwise you might as well just play the lottery

Once a couple of risky investments go to zero or close, it really puts a dent in the capital you have to keep investing " risky" and therefore the ability to play "catch-up"
Somewhere you have to have " dry powder" (in some very safe income producers) to keep "loadin' up"
Looking for the "Big Winners" is for the racetrack...or in other words this is a marathon, not a sprint.
Also, your 35% number is the failures...there's probably another 35% that are just flat....means you're going to try to shoot the moon with 30% of your money working.
Don't get me wrong, some things that some people consider " risky"..like emerging markets. or some hot retail, are NOT what I consider risky, they just need more watching...risky is putting it all on a company that has a" flloglee" when added to corn syrup runs a fleet of trucks for a month.( Yeah! companies like that are risky.

It's really hard to recover from a loss