Firstly, unless you and your co-founders permanently relocate, you could start to burn through that $500k pretty quickly in travel costs. Is relocating to the USA legal for you? Will it cost you more money compared to your current cost of living? Do you have existing staff or facilities that you would be unable to supervise or move?
The article mentions how useful to them YC's resources and team were to answer questions about business operations like finance and paperwork. How applicable would these be if you're not registered in the USA, even if not in a particular state? Would YC's advice with, say, employment law, have any value if you were incorporated in Switzerland?
The same points would probably apply to the benefits offered by any further early investors that YC could introduce. All in all, after taking away the 'overcoming imposter syndrome', 'answering boring questions' and 'founder community' reasons, it looks to me like an expensive way to get a bit of capital and credibility for those outside of the USA. I would be especially interested to hear from non-American YC founders who would beg to differ.