Traders can be also considered as investors because they take the risk in buying bitcoin. To buy is to somehow invest on it, because they also trust the potentials of bitcoin, it's just that the transaction is only made for short term.
However, when we talk about investors, they are mostly those who buy in dips and hold, and continue to accumulate and increase their portfolio through following DCA. They do it for long term, and only decide to sell portion of their coins when the price reaches a new all time high.
Yes ,true traders can also be called Investors too but the difference lies in their different time frames, approaches and endpoint goals they want to achieve.But sometimes,Someone can be an investor and a trader at the same time too.
Although,some traders and even investors would not want to credit the same influence of who's the trader of who's the Investor but in the long run,it doesn't really matter as they're good in identifying opportunities and effectively making profits.