With that many people maxing out something needs to be done to make dday come faster, else we will soon end up with 11+ people maxing out by the end...
Making it so you need to have the full 100% ship cost credits before you buy / resupply a ship could fix it... people max out because they don't get to max credits but rather 10% of that value and they design a max ship with max upgrades and then resupply and resell it for profit...
But if you have to have the full value in credits and then issue the line assemble / Gold discounts, that won't work anymore and they will have to get to the full credits value before buying the maxed out ship.