1. Totalitarianism isn't inevitably the result of communism. Totalitarianism is typically defined as the proliferation of the state into every aspect of life, ie no distinction between public and private spheres. The ultimate goal of communism is the abolition of the state, so obviously totalitarianism is counter productive to that end. It would also be incorrect to characterize every socialist country as totalitarian. Some of them were for some periods of time, for example Stalin's Russia and contemporary North Korea. Post Stalin the USSR could be called authoritarian for sure, but not totalitarian. This happened because Marxism Leninism, the model of socialism adopted by almost every socialist country, requires a heavily centralized top-down state structure, which I argue lends itself to authoritarianism. The solution is to implement a less authoritarian model of socialism.
2. Greed and naked self interest isn't the primary motivator in economic activity. If it were then you wouldn't have people die by the thousands for abstract concepts like religion or the nation. Even if it were, a communist economy would likely require a significant evolution in humanity, the technology to achieve post-scarcity, or both. Until then I don't see communism as achievable.
Socialism on the other hand doesn't preclude material reward in exchange for contributing to society. The real issue is how that reward is acquired.
3. Capitalism has five major issues that I like to cite: the exploitation/parasitization of the working class, the subversion of democracy, the inhibition of personal freedom as a result of wealth inequality, profit as the basis of economic production, and the loss of agency as a result of the market system.
These would all take a long time to explain in detail so I will try to summarize. Exploitation occurs because capitalists profit from the labour of the workers without actually contributing. Anything they add to the process of production (factories, training, materials, etc) is ultimately paid for by the workers, since anything the capitalists spends on their enterprise is paid for by profits which are be result of the labour of the workers. In this way the capitalist doesn't actually contribute anything, and is effectively a parasite. Pic related.
The subversion of democracy is obvious, we all know how easily big money has been able to put the government in its pocket. This is an inevitable result of so much wealth concentrated in so few hands. In addition, the workplace under capitalism is effectively a dictatorship. Socialism would make it a democracy.
This brings up my next point. Wealth inequality is a fundamental infringement upon the freedoms of the poor. Because your personal agency in life is directly tied to the portion of the world you can exercise your willpower over, your freedom is effectively tied to what you own. If you own something, you are by definition excluding others from it, and massive amounts of wealth can only be held by making sure others can't access it. This effectively means that the rich under capitalism massively increase their freedom while limiting the freedom of others.