Let’s clarify.

https://en.wikipedia.org/wiki/Soviet_famine_of_1930–1933

Are you saying that the famine didn’t happen, that the same famine would have happened regardless of the economic system, or something else?

I’m not against communism, and capitalists can make similar damaging calls.

https://en.wikipedia.org/wiki/Dust_Bowl https://en.wikipedia.org/wiki/Great_Depression

I think both systems tend to produce oligarchs through different methods. The point isn’t to pick a team and rally them on, rather let’s look at things honestly and consider information hostile to our viewpoints. I think it might be possible to build something better than both.

There was only ever one famine in the USSR, partly caused by kulaks burning grain. There were dozens of famines under the Tsars.

The same goes for China, there were dozens of famines under the emperors.

Communism ended famine.

Were those famines caused by poor political decisions? Possibly, but both countries were emerging from feudal subsistence farming, and had been ravaged by bitter civil wars. The position they were in meant even a single poor political decision could have caused a famine, if we were in that position today, with the leaders we have, we would all be dead.

I don’t understand “who supports it use products of capitalism”; does the someone want to imply that every product is made with capitalism? What is opensource then, when money isn’t the driving force of open source development?

How do you persuade them that you’re right or how do you come up with an argument that makes you feel like your chosen ideology does not have any flaws?

The first: you probably can’t. They are just as set in their world view like anyone else arguing on the Internet, including you and me.

Second: accept that all ideologies have flaws. Policies however well meaning have to survive contact with reality first and foremost. Or in this case reality has to survive contact with the policy.