Well I am brand new to all this but I have quit several different expensive hobbies over my life time, basically for the same reasons each time.
#1 Lack of time - Wife, young AND older kids, very busy / long work schedule, home and cars to take care of, pets, etc. Basically just living a life.
#2 Hobby expense and complexity - Lots of cool stuff in most hobbies and plenty of eye candy to buy and advertisers know how to sell.
Then you find from item #1 that there is no time to use it all or get to it to work the way you thought it was going to work as it was more complex to use than you thought. Gets very frustrating to see what you bought and aren't using and kills interest.
#3 Large Amounts of Conflicting Information / Advise - As someone else already noted and I am seeing in these forums, always conflicting information. If you do research, takes lot of time to figure out the pros and cons as to how things work. Basically any forum (hobby or not) you go to now a days, it gets hot and heavy on conflicting opinions.
Still working on getting my first ever tank (planted) together but my wife had a nonplanted one for ten years and asked I wait until we finish the redoing the living room which will be completed by July. Focusing on as much simplicity as possible with simple maintenance, once the tank is established. Almost in retirement and I have more time on my hands now so #1 is no longer an issue. Going with a 20 gallon long and gravel only using combined ideas from Walstad and Barr with the back up to convert over to somewhat more frequent water changes if the ideas don't work. I have seen enough videos of successful tanks out that there that I feel confident I can make it work with adjustments along the way.
Time will tell!