I invest in my own knowledge.

Investing (giving money) to a fiat company that promise me in return BTC, is just an IOU.

In a bitcoin world the term "investment" will have a totally different meaning.

If I produce something and I sell it for BTC, I will start saving more sats if I want to expand my business. When I will have enough sats to expand I will do it, but not with "investors".

If I do not have those savings, I will just remain with what I have. That's it.

Extending businesses it doesn't mean you HAVE TO get investors, but in a Bitcoin world it means a good funding management of not spending more than you can produce.