Dont feel bad if your assets are 30% down, just keep holding because it will recover for sure BUT this is only applicable for the coins with real use cases and well-established like bitcoin, otherwise you're rekt.
Op might be right about 3 years, referring to the time it took for Bitcoin to recover from the end of 2017 will the end of 2020. Nobody can say for sure whether this is going to be the case this time because for now, not enough time has passed to see the general tendency. In any case, people should be aware of the risks when investing in cryptos, and they should be prepared to hodl for years if necessary. I'm sorry that your investment is 30% down, but it's not anything out of the ordinary with Bitcoin.
I doubt it will take 3 years to recover, the situation now is different from the past. We see more adoption now and increased of users thus I think it might take shorter than usual to bounce back from bearish situation. Nevertheless no one can accurately predict the future of crypto but what im certain is, this is only temporary and we can see another recovery for the coming days, months or even it takes years.