It's the most difficult part of being a league admin. At first you are just happy someone joined your league then after awhile you realize too many owners will bail as soon as things dont go as planned or it may take time to build a winner.
The good news is that none of these teams has been crippled but bad contracts or serious cap issues like what happens in many leagues after 3 or 4 seasons. An owner will make a mess of a team and bail....for example in another league a owner quit leaving his team -114 million under the cap....yes negative 114 million....that francise has to cut the entire roster and will be a doormat for 3 to 4 years before any serious attempt to rebuild them can begin.
You will have owners that make horrible trades where they give up all there future high picks and still lose so they quit because they have no draft picks. You will have owners sign aging players to hugh contracts who retire and leave them with so much dead cap they cant retain talent, sign free agents or even afford draft picks so they leave.
Then you have owners in this league that for whatever reason purposely ruin teams and leave because that's what they do. It's hard to monitor every owner as league admin but for a league to be successful the league admin needs to be vigilant or you end up with teams nobody will take