I have seen many people who earn bitcoins and manage all their life expenses with it. I agree with you that investment in Bitcoin needs to be long-term. Because it is not possible to extract full profit from Bitcoin if not in long term. According to me, some part can be spent for special needs and the rest is better to invest.
The reason why long term holders makes more profit over short term investors is cause they allow the compounding value effect to happen on their bitcoin and bitcoin is a scarce asset that would continue to increase in value over time even if not at a faster rate.
If you look at what is currently happening the demand of bitcoin is high to the point that exchanges don't have enough liquidity to handle the demand of it, and you know what happens when an item is scare and high on demand, it's value would increase and this is not something that happens for a short period of time, you know that as people continue to buy and hold bitcoin the supply would continue to decrease making it to gain more value, so if anyone really understands the value of bitcoin as an asset he would be thinking in terms of accumulating more than taking profits off his holdings on a short term.
I am not saying making or taking profits off your holdings is bad but this should be after a period of accumulating at least enough bitcoin which is different for everyone but should be at a minimum of 4 years of accumulation. The only way to truly be prepared for up is to have more bitcoin.
And speaking of who has been more profitable, some person's that bought bitcoin right around when it was still at 30$ and sold when it hit a 100$ would have made profits from it yes, but imagine what those that kept their holdings up until now and see how many x and compounding value effect that has happened on their portfolio, so even historically long term holders have benefited from bitcoin more than short term holders.