Confusing as you already seem to have a drone profile as someone else said.
The "best" time for drone photography was about 2 years ago. Up until DJI released the mavic, it was quite hard or time consuming for people to get aerial pictures and there was quite a market.
Since then, the mavic, spark, air have meant that pretty much every person on the street owns a drone, can take their own imagery as well as submitting it to stock sites. The things are everywhere in daily life now.
You can still make some money if you already have a drone for other purposes but whether its worth actually investing one specifically for microstock im not convinced.
Especially with the current SS issue of image saturation and new images being punished and hidden in the search.