Risky but fast

[namloan]

1. Would your grandpa like to invest his money in something risky but earn fast profit or something safe but slow profit?

Could I use this sentence in conversations?

Thank you so much

[bwkcaj_ca]

Would your grandpa like to invest his money in something risky but earn fast profit or something safe but slow profit?

We don't use terms such as "fast profit" and "slow profit."

You could say something like:

Would your grandpa rather invest his money in something risky but
which promises a quck return or something that is safer but takes longer
to return a profit

[SoothingDave]

People invest in risky things not only for the promise of a quick return, but a large return.

[Barb_D]

I find an inherent contradiction in "risky" and "promise."

In expectation of...
In hopes of...
On the chance of...

There is no such thing as a "risky investment" that "promises" anything.