Bitcoin Dominance displays the percentage of Bitcoin market cap against the entire crypto market. You can see that it was 100% in the beginning since it was the only crypto. Since the introduction of other cryptos, Bitcoin market cap % tend to peak at 70%.
Right now, Bitcoin dominance is 62% due to its recent rally. Assume Etherem and other crypto stay where they are today, when Bitcoin rally to 100K, this percentage will likely reach 66% to 67%.
From there, there are two things could happen
1: Bitcoin goes through a sizeable correction and bring this dominance metrics down to 50%-60% range
or
2: Bitcoin consolidate between 80K to 100K, but other crypto play catch up and also bring this dominance metrics back to 50-60% range
In both scenarios, selling a small position of Bitcoin at 100K and buy etherem will gain more than holding Bitcoin at 100K.