Both major parties benefit from the status quo, regardless of which one's on top at any given moment or in any given district. I don't even know that it's about who ultimately wins the elections. It's probably even more directly about maximizing the amount of money that gets sent their way.

This suggests a short-term vision. I think it misses the mark.

Your opposition to RCV should increase with your distance from the center. RCV reduces the chances of fringe candidates being successful. Traditional U.S. systems reduce the chances of centrists.

Most intelligent strategists prefer to lose 50% of elections than to lose 90% of elections.

> Any party that already has high likelihoods of winning the election will be hurt by RCV.

No, it won't. RCV doesn’t hurt duopoly at all. It generally rewards the more centrist subfactions of whatever the two dominant factions would be without it, so if (in the USA) you views are best represented by a blend of the corporate capitalist neoliberal wing of the Democratic and the anti-Trump wing of the Republican Party, RCV is a boon for you.

If your views are not well represented in the current system, they will be even less represented with winner-take-all elections under RCV. For that, you need multiwinner elections producing proportional-ish results, whether party list, STV (the multiwinner system of which RCV/IRV is the single-winner form), MMP, or some other system.