More and more people come to see the Colosseum! After the 2018 all time record (7.650.519 visitors) in 2019 there was a little decrease. In 2020 there was the COVID closure but in 2021 museum were reopened.
The following table is from the official statistics of the Italian government.

Actually, the most visited Roman monument (more than 9 million visitors) was the Pantheon, as the entrance WAS free, therefore it does not appear in this table of museums’ revenues. Unfortunately, from this year the visit will cost something