1. You obviously don't know what the word "exponentially" means.
2. On a dirty grid like NSW an EV hits break even on CO2 with an ICE at about 50,000 km. In a cleaner grid like SA or Tassie, it's more like 25,000 km. When you say 5 years, are you claiming you only drive 10,000 km a year? That's about 30km a day, so you could get about with an old Nissan Leaf.
Even assuming five years - unless they get crashed, most EVs last way longer than that - plenty of ten year old Nissan Leafs on sale for about $10k of you want one. They've paid back the CO2 invested in them and more.
