I highly recommend long-term investing for those who are extra careful with risks. Not everyone can be a trader. If they are too scared of taking risks, they should choose a better alternative with limited risks. Splitting the trading capital into smaller parts, just like OP is suggesting, will not make everything perfect if the trader does not have good strategies. Moreover, they should not fail to understand that smaller capital leads to smaller profits. What this means is that the opportunity to make big profits might be missed if we adopt OP's suggestion while trying to minimize risks.
If there is a strategy available that's giving you good return with minimum risk then why go for taking risk? Bitcoin is now almost 15 years old and we are very clear that it's price will increase with time, slowly but steadily. It will be a big mistake if we ignore DCA and go for short term trading where nothing is guaranteed.
If someone is not investing today only because he has small capital then he must go and study the Bitcoin DCA first. The dollar value depreciate with time but Bitcoin value increase with every passing year, it's up to us to invest today to secure our future profit.