In my latest update I reduced the amount the veins spawn with, so you might be right about them being too scarce. I'll keep testing and maybe tweak the rates if the issue becomes more obvious. If you can get enough credits for an engine or aerodynamics upgrade, youll get more bang for your fuel buck.
Its funny that you call finding the black fuel unlucky, its actually the most valuable product in the game by about 5x. Its also great for ultra soft landings later on when the gravity increases and your engine becomes very twitchy. I find the red fuel is the least useful tbh.
Thank you so much for the feedback! I honestly appreciate it a lot. If you keep playing itd be great to hear if your opinion stays or changes.