It isn't easy to sit and be still, everyone who tried will tell you, you will find any kind of excuse to not do it. However if you endure it and spend some time meditating, it will indeed bring perspective and clarity in your mind.
These kinds of retreats are stupid... For number of reasons. Also 'apps for meditation' are extra stupid, except maybe Oak because it is just a timer, so it actually serves a purpose. If you really want to meditate, just sit and relax. OK maybe I was too hard on every kind of retreat, but overall they tend to be profitable endevours.
Because your mind will be maleable, cults love to exploit this state to program you and indoctrinate you.
Also... what happened to this girl is known fenomenon. It usually helps if somebody can tell you in advance it would happen. As I read article, they loaded her with drugs afterwards, not sure which is worse.
Again, cults = bad, you have everything you need to be happy.