Resident visa Sri Lanka (Colombo)

Hello everyone!

I've read on the website of the government that you can get a residence permit for one year by investing in the country.
Is that the only way of being able to stay longer than Protected content ?
I'm a writer and am looking for a quiet place to write a book and I'm in love with Sri Lanka so far.
For me a stay of Protected content would be perfect, is that possible?
Me and my wife (Canadian) would also like to visit Sri Lanka to see if we can find a sustainable business opportunity.
We love the fact that there's buddhism, yoga & and surfing and both have our history in teaching and school projects.
Therefore I'm wondering what our possibilities are for a longer stay in Sri Lanka are.
Is there anyone who can give me a taste of their experience? Is it doable?

Thanks in advance and wishing you all the best,

Hugo Alexander Rijpstra (the Netherlands)