As much as they’ve seen how bitcoin price drops drastically, then they should also learn to anticipate that bitcoin might reach another all time high when bullish market takes over the bearish market. That way, they will always remain positive on the bitcoin price, regardless how volatile it is. Otherwise, they should not be in crypto in the first place.

I think the only set of of people that need reminder are the newbies, as a professional am sure you should know the current bear market is normal, we can't just continue to see the bull run without the bear market, any professional that is scared of the current situation or that's disappointed should just leave crypto space, I don't think their is anything that can motivate you.
I think this apply to only new investors, Bitcoin is not a get rich quick scheme, most newbies get discouraged whenever they invest in bitcoin and they see their money reducing on a daily basis, most of them endup falling for some tricks by scammers which will ask them to invest and they should be expecting double of their money in few days or hours.
I believe every year their is always a time when bitcoin is always down, so I think people that have stayed long in crypto space should understand that the current market condition is normal and is just temporary, with time everything will definitely bounce back and everyone will smile again.