Wouldn't that be simply just through govt T-bills which have almost no risk.
To be honest many things are fairly safe in the long run unless you get completely burned in the short run.
Nothing you can really do about that. I would just do T-bills
T-bills have the lowest risk, (unless government crashes). Trying to make $100,000 in one year from another $100,000 "risk-free" is just not going to happen. We can be 95% confident that you make a certain return and in general a 20% return on 100k is actually pretty good in monetary terms. Risk-free rate is generally 2-4% depending on a countries inflation rate so if you are beating that then you are doing great.
Risk free if you put your money in the bank, it will earn a little interest but you can be sure you can double it in due time but how long can you wait for that to happen, I think we cannot get the value of our money because of the inflation rate. There's no safe way actually as when you invest you need to bear the risk.
Thats really a safe way to do if you want not to risk your money at all on any investment but just like what you said no one would able to wait for that long hence interest on bank are too low on annual basis which do only gives only small percentage on our money and not worth for the waiting time effort though. If you really need profits then you must risk your money in able to earn decent returns.