I think it depends upon where your interests lie. If you are interested in any of the upcoming titles like Remnant 2, Baldurs Gate 3 and Starfield, then I'd probably say maybe hold off for now because those titles have several hundred hours of gametime in them and you may well find you end up playing them more than D4. If however you're not really into Baldurs Gate 3 or Starfield then I'd say sure, go ahead and get Diablo 4. If you got thousands of hours out of Diablo 3 then I'm fairly safe in saying you'll get hundreds of hours out of Diablo 4 too. Time is the bigger constraint imo than money, comparatively speaking the cost of Diablo 4 is peanuts but with only limited gaming time available and the big timesinks of BG3 and Starfield on the horizon, that will likely be the deciding variable to weigh up.