No doubt, dca strategy has enormous benefits as regards to Bitcoin investment the reason why it dominates the thread, but on the contrary a lump sum buyer can as well be successful in his Bitcoin investment,  in my opinion that lump sum buying can as well leads to significant returns, you can actually set up a portfolio through the lump sum buying and allow it to grow. the very best strategy is any of the strategy that allows an investor to hodl his investment and sleep well at night, whether it is dca or lump sum, the main factor to be successful or not in Bitcoin investment is the ability to hodl long term to take advantage of it's comp youounding value,the right strategy is unique to every investor that is why it is of great importance for any investor to tailor their strategy to their own risk tolerance and financial situation as well as their own conviction level to prevent a situation that could lead to emotional decision and selling too soon.
 My point is that dca is not a must to be successful in Bitcoin investment according to @Fiasem20