Will add my few cents from the E-Challenge perspective.
Soooo, I was facing this exact problem in the E-Challenge too. While not so severe numbers (mainly due to extreme hype), the trend was clear, and thanks to my decision to host only 3 rounds (if it is a shitshow, at least it's soon over) we stayed in reasonable attendance numbers even at season finale.
To put things in perspective:
52 drivers did successfully register for the championship (50 were valid)
41 drivers did attend at least 1 round.
14 drivers did attend all 3 rounds.
R1 had 32 cars on the grid.
R2 had 26 cars on the grid (28 attendants)
R3 had 20 cars on the grid.
The trend was clear - interest was dropping significantly and if we had 5-6 races, the finale would have like 10-12 cars on the grid... (
E-Challenge 2020 flashbacks)
I struggle to understand why it is happening - I sent a survey to all drivers who did attend at last one round of E-Challenge (full results will be published soon after E-Challenge is officially over, but will leave few thread-relevant things here anyway)
In one question i was asking, what was the reason for missing out any round (keep in mind these answers are from active drivers, not those who registered but never showed up - I'm fine with no interest from the beginning, but don't understand increasing lack of interest over the series)
* last 3 answers are open answers
The strong majority had real life stuff to take care of (which is understandably a higher priority), guess we cannot do much about it, but it does not answer why the attendance drop is chronological. Rest were technical issues, bans and whateverthe****didtheymean.
I was also wondering if we could pick a better time for the event, however those who voted did pick same or similar timing as what we already have, so no clear evidence we are doing it wrong timing-wise. (There was open answer available as well, but only 1 response was a non-weekend day, rest did stick with the weekend evenings)
TLDR; still don't know what is causing the drop in attendance, or how to effectively combat it.
All the methods I was hopeful with did not work and I'm out of ideas on how to motivate drivers to keep racing.