Are you being intentionally dense? The point that doing HNMs was a net loss for many shells is an objective stance. The fact that people did it in the first place indicates that they enjoyed the content to some degree, or just didn't know better.
Objectively? Farming gil and buying drops was better for a hell of a lot of stuff. Still is. But unless some people find Arch Dynamis Lord super fun and thrilling and totally worth doing regardless of the drops, you're going to have to weigh people's proclivity towards the event against the opportunity cost they incur by doing it. Every relic taken 95-99 is essentially another 75 Relic that could have been built from scratch.
You're also completely convoluting the issue. It's not a matter of people entering Dynamis or not entering Dynamis. They already entered Dynamis. The opportunity cost being weighed is what they're doing after entering Dynamis. They're there. They have a choice between farming ADL and farming currency. Farming ADL means not farming nearly as much currency. That is a loss.