If you possess a lot of past experience, you likely have a good idea of what works for you. Spend $5000 if you want to, but it surely is not necessary. Endurance/gravel type bike with a more relaxed geometry is a good choice for versatility. If you just do a specific type of riding, maximize the bike for that, or, split your budget and get 2 bikes. I have been a cyclist most of my life, but I really got back into it in 2014 at the age of 61. In those 10 years I have put 50,000 + miles on my bikes, and acquired the tools and knowledge to work on them myself. This past year I got in 6500 miles, despite some time off due to medical issues. Cycling is a very big part of my life. Now I am heading into the reduction mode. Curiosity, what size bikes are you looking at?