Would probably need less than 50k for a reasonable requirement, since the playerbase might not quite be sizable enough to support that without a good length of time. Time investment for the overall community is important. We already technically spent currency in Libra to get places so it's not like that'd be a big change. Still, make it a reasonable community goal within Libra, arcade, or maybe a simplistic alt mode and it could be interesting. For incentive, maybe make it be customization parts, weapons for styles, or alt. colors/costumes that auto-unlock for all players if the goal is reached. Obviously other things could be involved too as rewards, but that would make for a way to make the idea more appealing. Would probably get people playing a bit more often too, with something new to look forward to going after regularly aside from rank.