But even if you ignore that limit, at that kind of speed you also need to account for your outer hull undergoing significant damage as each stray intergalactic hydrogen you hit has a kinetic energy of 34.75 TeV in your frame of reference, and while this will create a large supply of antimatter, it will do so in a way significantly less helpful to your goal than the fact we can transmute lead into gold by using the former as a radiation shield in a nuclear reactor is useful to someone who wants to get rich quick.
Bonus fact: this energy level is higher than the LHC, so you may have some extra weird mass-modification effects besides relativity as the front of your spaceship is now a Higgs Boson torch.
http://www.projectrho.com/public_html/rocket/enginelist3.php
But even if you ignore that limit, at that kind of speed you also need to account for your outer hull undergoing significant damage as each stray intergalactic hydrogen you hit has a kinetic energy of 34.75 TeV in your frame of reference, and while this will create a large supply of antimatter, it will do so in a way significantly less helpful to your goal than the fact we can transmute lead into gold by using the former as a radiation shield in a nuclear reactor is useful to someone who wants to get rich quick.
Bonus fact: this energy level is higher than the LHC, so you may have some extra weird mass-modification effects besides relativity as the front of your spaceship is now a Higgs Boson torch.