Have you tried typing what is Bitcoin in a search engine online? The answer will be digital currency to be precise but while going deep you will find more use case, e.g.
1. Decentralisation
2. Store of value.
3. No extra printing like money (Limited in supply)
Now it's left for you to pick a side as to what you really need Bitcoin for, use it to your liking, many have comfort in using Bitcoin to make payments online like using credit cards and I do that too but store of value is more interesting to me than anything else.
If you want to know what bitcoin is and to get the most accurate answer, you should read its white paper, not search for answers online.
But OP's question is what do people today perceive and consider bitcoin to be, a currency or an investment? And if we're being honest, it's clear that the majority of people, including you and me, just see and use it as an investment more than any other use case. We have turned bitcoin into a digital asset for storing value and investing, rather than using it for the purpose Satoshi originally created it for.