If you're genuinely looking to make money long term then you need to focus on more obscure stuff. Local leagues are good. If you're English there are all the non league stuff. Teams have sloped pitches, long travels, players missing because of work and loads of other things not factored into prices. Likewise with other lower leagues in countries, Austria, Denmark, Italy, Belgium etc. Youth football is good to follow as well but takes a lot of time. Womens football pretty easy as well, doesn't take as much effort as youth since squads don't fluctuate near as much, players moving up an Age group etc. Most people don't realise the potential goldmines they have on their doorsteps.
Obviously this is just my opinion on how its best to make money long term, betting purely for profit as opposed to any interest/enjoyment.