The markets that are basically derivatives of financial products (qqq/spy closing price, oil, rates, etc) have pretty decently sized volume but are likely pretty efficiently priced and most likely have institutions market making on them.
The more niche markets are orders of magnitude smaller and are probably less efficient. However, market making on some low volume, niche market probably won't pay much.
One of the exceptions to that was of course the recent election, but events with such high volumes on that scale of unpredictability are quite rare.