Because you are trying to give Goku a 1000x FTL while nor he, nor anyone he scales from, ever showed to move at such speeds.
You just calculated a single feat and applying multipliers to it over and over.
You calc a speed feat, make that their base speed, then you apply a multiplier making that multiplied speed their base speed, then apply multiplier again to the new base speed that was achieved by multipliers and then make the newest speed their base speed again, and you repeat.
This is just absurd multiplier stacking, if you don't have feats that put characters on such absurdly high levels, then don't put them there, maybe it's not their level.
There are no speed feats, only scaling.