[logicalmonster]

You could probably cite dozes of contributing reasons ranging from Covid fatigue, the number of entertainment options exploding, and peoples' attention spans being more limited.

But I'd speculate that one of the biggest factors is the feeling of postnationalism.

Being from a specific nation means almost nothing anymore. There's basically almost no such thing as a Frenchman or a Brit or a Canadian: these are just treated as arbitrary designations today. If everybody everywhere is the same and the nation is treated as irrelevant, then an international competition means much less.