For years I had a few basic power tools, a Table Saw, Miter or Chop Saw, and a Router.
Then over time I started to build up my tool collection. I am still building to this day. My father taught me to invest a portion of every project back into my tool needs. He said, "Your tools add value to each project, make sure you charge a small amount to cover those costs."
Some projects justify the purchase of a tool. If I need a trim router for 3 separate steps, each needing a different bit. When it takes me 10 minutes to change that bit, it would be better to purchase an extra router. My time is a value. If I can complete the project in less time, I make more money!