We should think more about the risk of having all your investments in one single portfolio, such as bitcoin. Bitcoin happens to be the most reliable cryptocurrency for investment but at the same time, Bitcoin is a highly volatile asset. So I will still advise you to diversify your portfolio into multiple sources.
You don't have to diversify because, as you said, bitcoin is the most secure cryptocurrency. But if bitcoin is having a bad time, any other coins will feel even worse. So don't buy the whole deposit at once, but buy in parts. That would be the best strategy. And if the market situation becomes favourable, you can consider buying other cryptocurrencies.
You do say about increment purchasing or buying? Its not a bad idea since there are people who do really accumulates on everytime they do see bitcoins price plummets and solely focus into this one rather than making
some consideration on some altcoins in the market.Giving out guarantees are shit ones on which we cant really that able to tell precisely on what would gonna happen in the market even in talking about Bitcoin.
Thats why the golden rule on this market is never ever tend nor plan to all in even whether you are a noob or a veteran but we know the main differences when it comes to decisions to be made
which is totally situational and depending on someones skills and awareness towards the market. Dont go all in because whenever things out of hand then you would really be finding
yourself in big trouble.