Why wouldn't it be? Wealth is created, and if you can create a billion dollars in wealth, then so be it.

Even if so, is it right that you can be a billionaire while there are more empty homes each night in the US than the homeless population?

Depends on what you mean by "right". Is that a troubling, even disturbing situation? Yes, I would find it to be so. But is any particular billionaire (or any other particular individual at all) somehow obligated to fix the homelessness problem? No.

Is it right that you can safely eat anything you like while others have to make sacrifices and choices because of political cuts to SNAP? The answer is clearly no.

I would disagree, again with the caveat that it depends on what you mean by "right". I think I would rank that situation as "unfortunate", and I think we all wish the rich would do more to help the less fortunate. I know when I was dirt-poor, living below the poverty line, I resented the rich a bit, so I get this mindset. But as I've moved through life and seen what hard-work and determination can accomplish, and become more comfortable in my own skin, I find that I no longer cherish the idea of handouts greatly, except for the real edge cases: People who literally cannot fend for themselves - the elderly, children, people who are physically or mentally disabled, etc.

In this way, pursuing money for wealth's sake is unethical.

I guess this also depends on how you define unethical. Is a really rich person who does nothing to help the less fortunate a huge asshole? Arguably, yes. But is that the same thing as behaving unethically? I wouldn't say so. But I expect we have fundamentally differing worldviews on some basic issues, so I'm betting we'll always disagree on this.