Say someone wants to take your service down, you've got 500Mbits line at home ISP, and 10Gbits on your VPS; they sends 1Gbits of traffic to your VPS, your VPS happily tries to forward 1Gbits, fully saturating your home ISP line. Now you're knocked offline.
Say someone discovers the actual IP, dropping traffic from anything else other than the VPS doesn't help if they just, again, flood your line with 500Mbits of traffic. The traffic still flows from the ISP to your gateway before they could be dropped.
Say someone wants to perform SQL injection on your website, there is no WAF in this stack to prevent that.
Say someone abuses a remote code execution bug from the application you're hosting in order to create a reverse shell to get into your system, this complex stack introduced doesn't protect that.
You've provided a comprehensive guide, and I don't want to single you out for being helpful, but I must ask: What problem does this solve, and does OP actually have the problem this stack can solve? From the replies we've seen in this thread, OP doesn't have sufficient understanding to the full scope of the situation. Prescribing a well intended solution might be helpful, but it gives a false sense of security that doesn't really help with the full picture.