I think there are two very different ways of participating in a loyalty program and trying to maximise the benefits.
Some will chase status in the hope of getting lounges, better seats and the chance of an upgrade. That's potentially going to cost a lot of money, and perhaps more than the benefits you receive. The international upgrade lottery is an example of squeezing every last dollar out of someone... you need to pay a higher fare just to be in the running for an upgrade, and you try and get platinum so you can be at the front of the upgrade lottery.
The other is not by chasing status, but availing the other opportunities... like buying miles. Many of us will have saved many tens of thousands of dollars buying miles through US Airways, American Airlines, Avianca, United, even British Airways (avios). The airlines are still making nice profits off all those sales, but we as consumers are also benefiting through much lower fares. Generally you are also protected against mileage devaluations because you buy the miles for a specific award (buy and burn fairly close together).
By not chasing status you also have the freedom to mix and match airlines, and take advantage of opportunities such as the Oman Air $500 business class flights from Asia to Europe (crediting to EY so you can get a free US domestic flight on AA at another time

)
There is of course a third category... 'passive' participation. You accrue points through every day spending, but don't go out of your way to buy anything you wouldn't normally buy, and aren't tied to a single supplier. The risks here are very low, but so are the rewards.