The NBA is doing what it is designed to do - rotate teams at the top. It's really hard to win more than one finals. For as stacked as the Celtics and Lakers have been the last decade, they have also only won one Championship each during that time. Celtics were in the conference finals six times before they broke through and won the title in 2024.
The cap, the aprons, the draft... it's all designed to rotate who is at the top. You have to get really lucky in the draft on multiple picks and/or have someone make an absolutely stupid trade with you (OKC) to win multiple championships (and OKC hasn't completed that yet).