may or may not  make 'more' than farming... but   look at it this way;     If  he is adding to his bottom line,    without  leaving the place..  it's  a  win/win. 

He  certainly could  go into town,   stand behind a parts counter for 8 hours.... 'adding'    to his  income.  then  race home and work until  2 am on his own stuff.

OR-    he could   document  what he's already doing,   and   actually  have time for a  family. and  some sleep.

There's a  YouTuber  up In  Washington State,  that's a  smaller alfalfa  grower,   that  supplements his hobby of  aircraft  with  a weekly  'show' of life on the farm, inside the house,  inside the hanger,  and on air adventures  to places  across the nation.  
Most farmers  couldn't justify  1 plane,   this  guy has 6.  I doubt the  tons of  alf. he sells could  support  just one. 
     Granted,  they aren't   Cessna's, Pipers, or  Cirrus's...  
 but are more of the Experimental/ultralight  version..   

He  does  product endorsement  'commericials'  intermixed  in his  broadcasts.. 
multiply that  with his  147k  subscribers,  and  i'm sure it's a  decent chunk of  cash.