Why the Thanos do not offer infinite resources ranther than kill half of the humans?

Sure it sounds like the easiest and most humane answer but if you think about it there could be overarching long term problems. If Thanos just wanted to save a world then this would be a terrific way to help them. Give them the food and resources they need to provide for a rapidly expanding people. Only problem is at some time the people of this globe will run out of space to grow into, overcrowding becomes a huge issue. Not to mention the destruction of nature and decreased quality of life that would come as a cost to provide housing. And I would like to buy the custom made cosplay costumes .

Well the answer to this is that this population could travel to space and habitate a new world. Two problems here, one is that requires this civilization to develop space travel and world migration technology before they hit some overpopulation point (which may happen very rarely across the races of the galaxy, we dont know for sure).
And the other problem brings us back to if Thanos only wished to save 1 species. If we consider the entire universe then we realize that there would be countless areas where 2 species start colonizing the galaxy too close and too quickly to each additional. This may end up with massive wars, slavery, extinction, etc. Who knows, maybe the net result of this scenario is an overall decrease in the quality of life over the entire universe? Thanos would end up having to manually balance and good tune each civilization and their unique scenario in order to make sure each globe has enough space to colonize their galaxy. Even with the infinity gauntlet this is an infinitely time consuming quest.

So providing unlimited resources throughout the universe is certainly merely a short term solution that prolongs the inevitable with a chance of greater net decrease in standard of living for the average population and would require an unattainable amount of effort on Thanos's part. As opposed to snapping his fingers every couple hundred years or so. And you could also buy the green arrow and black canary costumes
TLDR; Unlimited resources doesnt solve the overpopulation issue on a universal scale.