When it comes to Bitcoin investment, just like the title of topic implies it's just best to "buy the dip and hodl", this is far better than thinking you could accumulate through trading which is luck base like you have already stated. Sometimes the availability of funds or finance is a major problem and also goes with impatient, many Bitcoin investor are mislead by the false stories about how trading is easy and actually try to venture into it by thinking they can get some Bitcoin added through this means to their investment but believe me it's not as easy as they make it seem in the ads and commercials and I Know this through the hard way(lost some coins).
If anyone actually want to be successful then keeping a strict mind about their investment would go a long and also knowing exactly when the market favours you so you can buy more (during dips) because you get more Bitcoin when you buy during dips or you can just go with weekly accumulating and most importantly never use funds that you know will affect you, thereby making you temper you Bitcoin investment.
The main option is also not wrong because some people may divide their fund allocation in half in investing. I mean they apply 50% for the long term and another 50% for daily trading or they buy when prices are low and sell when prices are high. So of course they can allocate the profits they get for long-term investment. And it's also not wrong because they take advantage of dips to buy and sell when prices are high and also they have long-term investments in the 50% of the funds they own.
Every strategy that is best for gaining profits is definitely of great interest to traders and they will apply the best to collect BTC for long-term investment. Apart from that, the moment of decline is always the best choice to buy more aggressively with what they have done before. So I also agree with you if you buy at a low price and hold it for the long term.