I think you are missing my point, I value life too and I never said Thanos' plan is correct one. The thing is if we double the resources it will create way more problems in long run( especially in case of humans) . I am a student in the field of astronomy ,and one of the thing I have learned about our current capacity to colonise Mars , to put it simply in next few years , we can have research camps set up there for extended periods of time( there are lot of factors which I will probably not talk here) . Now the question is though , Should we colonise it? I mean for exploration purpose, sure , but at the our current state , humans will probably cause more destruction than development. Let me put it this way, Our Planet Earth has enough resources to last humans for a long period of time but instead of using it properly , you know how we are doing it. Most Humans, if not all has one bad habit, they will not work towards solving the problem if doesn't concern them directly. They will either ignore it or spend more time on fighting with each other on how to solve it rather than taking steps.

I 100% agree on the point that what Thanos did was wrong but he was not a complete idiot , Infact he depicted the same traits which sometimes humans have that is getting overconfident, being egoistical.

1) He told his people about his plan, his plan was rejected and then bad stuff happened without him interfering anyway. In real life it happens, sometimes a person gets so overconfident that he loses sight of people around him. He refused to accept that his idea is wrong but if things go wrong without his input (idea) then it boosts his ego way more and he says ' I told you so , you guys didn't listen to me' 2) Thanos actually executed his plan on other planets manually ( before stones) and found out that his plan his working . Now tell me Thanos , a man who has lost himself in his own ego, who refuses to listen to anyone actually manages to succeed by executing a plan which otherwise would not work ( for the most part). His next logical step ( In his own mind) is to execute his plan on a large scale ( Remember Thanos never did enough research , he never even considered other options). 3) He not only thought this his plan will save the universe but he will actually teach People a lesson . Remember that according to Him( and is somewhat true) , people are greedy and even if he chose other options people would do same thing over again.

Now we know that his plan wouldn't work as people would repopulate anyway in few years BUT he doesn't know that, his plan has definitely worked somewhere in universe .