I don't think giving a discount on the start of the arena will make buzzerbeater an "instant gratification game". Even with an Arena built up, buzzerbeater is a slow grind and requires patience and long term planning.
I simply believe that arena expansion takes unnecessarily long at the moment and isn't exactly the most exciting aspect of buzzerbeater. Giving a discount on the first 5000 or so seats would just change it from taking 7 million to something like 5 million in the long run. Still a grind, still going to take a long time, but new players also have some more money to invest in trainees or attempting to compete.
I also get that in a lot of countries this is less of a problem as you can start in division II or III and have a much higher income right away.