Increasing reliability of a hardtail MTB
There's no point replacing the fork. A better fork will be more robust but replacing a major component is not cost effective. A better fork will cost a significant fraction of the whole bike as a separate component. If you want a better fork you should have spent the money buying a higher spec bike in the first place.
Wider tires are relatively inexpensive and will definitely help smooth out the trails. Go tubeless if your wheels allow for it as this will allow running lower pressure without risking pinch-flats.