People here are thinking too much about "how Levi can use more gas than the rest of the people".
TL;DR: Anyone can go super fast like Levi, but most people do not have the ability to use and using it wrong would most probably kill the user.
ANYONE can use a lot of gas to move fast, Eren did this as well and almost died. Mikasa did that as well and almost died. THAT is the answer. You can for sure use a lot of gas, but do you have the skills to use it in an efficient way and know how much you can keep going before you get stuck without gas in the middle of titans?
Almost no one can reach this type of ability, and THAT IS FINE. Not everyone is a superhuman like Levi. Mikasa is the best one in her squad and became stuck without gas in the middle of the titans. Using a lot of gas is useful just if you can use it well enough to be worthy.
I can go further and I will cite this utilization in real life: one F1 Racer, maybe the best one yet, Ayrton Senna had one technique in his races, he made the turns using the thruster, brake, and clutch at the SAME TIME. Just like Levi, he burns a lot of gas and needs to refuel more often but he got a super advantage because his motor was with super high RPM at the end of the turn and because of that he got a huge edge against his rivals. Any other racers that try to use that technique that can't control the 3 pedals will burn more gas, can miss the turn, and even cause one accident. So for the other racers, is it really worth the risk? Mostly no, unless you are a genius.
And that's the reason. If you want to go even further, to use the DMT fully, you need not only incredible reflexes but also needs to fix the hook in ways that you can use your previous thrust to increment and keep going. If you go fast and your fixpoint is bad, you just burned a lot of gas to go faster and a lot more to go slower. It is one huge disadvantage in the SNK universe where gas is very limited.
So that's it. The bonus part is that if you go too fast, you can also hit something and die. And in SNK, it would definitively happen.