My VPS provider is running a promotion where I can get up to 5 additional public IPv4 addresses for a one-time cost of $25 each. I have always only used a single public IP address per VPS. Would there be any advantage of having additional public IP addresses?
I know some people do not consider a VPS self-hosting, but this is the most relevant community I could think of and the question is also applicable for homelabs as well.
You could run multiple mail servers. Or download from Sharehosters in parallel. Or download more Youtube videos before the rate limit stops you. Or use virtualization or containers to launch some more virtualized servers.