Agree, there's no guarantee with bitcoin in terms of gaining profit. Since if someone claim that they could give you a sure profits with bitcoin then ask you to go with them, start to doubt with that since provably they have bad intentions with you.
I presume that your ascertion that there's no guarantee with Bitcoin investment in terms of making profit is just a function of trying not to become too ambitious with what you're expecting from your Bitcoin investment.
Even though there might not be 100% guarantee in Bitcoin investment (which is similar to all the other investment choices), there's still at least an 80% guarantee that Bitcoin is a good store of value and that if you buy Bitcoin and HODL it for the long term at this current price, you will be in profit. I wouldn't advice anyone to go all out trying to convince people to invest in Bitcoin with promises of getting massive returns from it but at a set out date but for the long run and using the DCA methord, I can comfortably talk anyone into investing as long as I'm certain the person has a long term intention in view.
What makes bitcoin good is less supply and it have huge demand so we can really look forward for more pump with this coin.
Bitcoin is not like the coin out there that just pumps because of some random hype that comes about due to seasonal demand. The demand for Bitcoin has been at an high rate right from the past and till date, Bitcoin is still in high demand and in addition to that, Bitcoin also has a lot of added quality apart from demand and it limited number in circulation which is what has helped it to remain dorminant throughout all these years it has stayed. Of course when you add all the uniqueness that comes with Bitcoin, you just know why it stands out and shouldn't for any reason by compaired to all the coin in circulation.