Since you say native resolution I assume you mean the highest resolution and bitrate available. Because playing the native resolution of a DVD is way way worse than streaming.
Buying everything on Blu-ray and 4K Blu-ray would be very expensive if you watch. It's also not very convenient.
There is absolutely nothing wrong with buying Blu-ray's but don't pretend it's the perfect solution to all the problems.
You said "own" though.
I pirate too but it's not ownership.