Even if you do everything correct, including continuing to DCA invest into bitcoin for the next 8-10 years, it is not guaranteed that your investment will end up being successful.
Yes, bitcoin has been a good investment, and there is no evidence to suggest that bitcoin is no longer a good investment, but it is still not guaranteed to pay off, even 8-10 years or longer down the road. Each of us needs to size our investments accordingly, without anticipating that our investment into BTC is guaranteed to be successful, when it is not.
I do lay emphasis on this too, accumulation shouldn't be limited within 10 years or we expect to already make profit, even if we do, investing and accumulation should be taken as a life process and security for the future. Bitcoin is our digital gold and should be treated as a such not just for profit making sake. The goal should be sticking to your investment plans in a way you consistently invest without getting worn out.
My point is not so much about the timeline exactly, even though I agree that having a longer timeline should allow for pacing of the investing - yet all along, any of us should know that at any time, our investment in bitcoin could go to zero, so we could lose up to 100% of our investment, and we could also lose some variation in-between 0% and 100%, since bitcoin is also not guaranteed to make any kind of a profit.
There surely is the other side of the ledger that should also establish that it is possible for BTC prices to appreciate greatly, so that remains part of the nature of an asymmetric bet.. a possibility of losing up to 100% (and no more if you do not leverage), but also there are various upside possibilities too, that contributes to abilities to potentially profit several times more than 100%, depending on how either side of the scenario plays out, and surely there have been many of us who have already profited stupendously in bitcoin, so we likely have decently sized profit cushions, yet there are also people who are more recent entrants into bitcoin, and surely bitcoin's price is generally up so a large number of folks who have been buying regularly and consistently over recent times are likely to be in profits, even though more recent entrants may or may not be in profits, and new entrants into bitcoin have to consider the various ways that they might want to get into bitcoin, including my own ongoing recommendation that anyone new to bitcoin should get started right away, and sure s/he may have to figure out details at a later date.