Any investment that can at least last a two year of holding should be profitable, also for those interested to invest and go to this extent or even more using the same approach, then can targeted at buying the dip and holding, this is more advisable to do, because it will not be more interesting when after we buy at high them the market begins to fall, instead its more better that we buy at every dip and continue to hold until we are profitable.
Not all investment that last for a year or two will be profitable to the investor because when you consider how long the bear market stays, you'll realize that some projects dies before the bear market is finished. Bitcoin also falls very well during this time therefore a year or two is too small for an investment to give you profits. Some people get lucky that after they invest, their investment doesn't stay long before they realize profits but for a project to give you profits, you'll have to hodl for a long term and that's why investors with good records are always long term investors and not those looking for quick profits.
2 years might feel like a long time it is like forever timeframe, but in crypto it is not always enough especially with how deeep and unpredictable the bear markets can get some altcoins don’t even survive one full cycle and that is where long term patience really matters a lot. Bitcoin is kind of different though because history has shown that holding through multiple cycles like 4 years or more kind of pays off at the end, even when short term dips look scary most times. that is why many seasoned investors preach long term holding over chasing quick flips and fast profits. At the end of the day it is not just about how long you hold!! but what you are holding in your portfolio. Because strong projects survive the storms no matter what and weak ones fade away...