Unless it's mandatory, it's useless. The very people who do wear masks aren't doing it for themselves even when they think it is for their protection. I'm at a football match tonight with over 54,000 others and even from the first day back after lockdown, fewer that 10% wore masks. Everyone had a mask with them but once it was seen nobody was bothering, the masks were discarded.
While people make their own decisions and weigh up their own risks, what is of concern to me are the disabled supporters who'll be there. Apart from an entrance just for them and their helpers, once inside, there is no special treatment for them, just their allocated spaces at the front of the Main Stand and the one I stand in. In the concourse underneath the seats, they have no choice but to mingle with everyone else. I'm assuming some if not all of these disabled supporters will be in the vulnerable category so are in need of extra protection - which they will not get.
What should have happened is that when even the limited numbers allowed in (5,000 or fewer) had to wear masks, it would have been easy to expand that and get the message across once we were all allowed back in again but this measure wasn't taken.