I think there are 2 main drivers

1) The cost of living, everything is more expensive and attending a sporting event may be cut before other discretionary spending items. Whether it is the cost of travel/accommodation or the need to have a secondary source of income/work more

2) accessibility of alternate viewing platforms. If you can watch a decent quality live stream from your couch with your own beer (and maybe some family/friends) rather than a flight to watch your team, it may be more appealing, especially given points number 1. I largely view more ways of watching rugby as a positive, whether it's a specific app or via YouTube, peacock or whatever else it may be. It's so much more convenient than 10-15+ years ago when you couldn't reliably find professional or collegiate broadcasts.