If you pay for something, you should get it and that's pretty much it. Make selfbetters part of the regular nudgeline (that's what I do when I host). Nudge to 1st is bullshit and is pretty much just ripping people off.

Or just make it so that you can only nudge selfbetters every second round, that way the line moves at least (or you could just nudge to 1st, then 3rd, then 5th... and so on depending on the length of the nudgeline.)