Yah. The longer BTC is held, the better the profit would be. The price has increased now and it is going to go more. Many have already seen the profits and again bought more bitcoins and holding it looking for a price more hike. Too much investments now would pile up the wallets with good profits. Almost everyone is waiting for the moments to cherish.
i agree with you and you are right that longer bitcoin holding is very profitable and adoption of bitcoin increasing and bitcoin price is also increasing too much quickly day to day and people buying bitcoin and then hold it for high price and its way is very profitable .
Depends if you are holding a lots of bitcoin and it takes a long time before you can get the hug profit, unlike you are investing in trading that you can make a good profit if you are invest in ICO's but depends if what altcoin you choose always research first so that you can lose in the future..
But nowadays due to a lot of scam ICOs I will say that it is better to not to invest in any other place but have to keep these bitcoins for longer and to wait for the price of bitcoin to increase in value that is the best investment and a way of profit.