Bitcoin is a cryptocurrency and by that we mean that it is a digital currency that can be used in exchange for either goods your intend to buy or services you are offered or offering.
Nope , you can use it as a means to buy or sell items online . Some companies use bitcoin to buy stocks online and it helps them to use less money .. this is an advantage if you know the cryptocurrencies world well. So it isn't for investment but also another currency for exchange
I don't think bitcoin was created for investment it was created as a ayment form so that common people can eliminate the banks and receive faster payment for lower fees. But over the years bitcoin evolved as an investment asset.
Bitcoin is a way of storing wealth, as it would increase in value over time if you can wait for it and have faith in the project, you also need to be patient as there would be rise and fall in the process.