I would very much doubt that anybody takes it lightly, you may not mean it exactly like I have read it but it reads like you think they are just sitting there and going 'You know what I'm going to get rid of my penis tomorrow' or the alternative 'Oh, those penises sound good, might go to the doctors tomorrow and see if they have any in stock'.
People talk about this subject in such a blasé manner, a way that they feel that the person involved hasn't thought about this for their whole life.
I would say that their doctors, and other people involved would give them a lot of consultations, going through the physical and emotional aspects of the procedure, etc. I would personally refrain from saying therapy as there is an implication that they need to be 'cured'.
As this is a thread revolving around politics, I would also add that this issue should never be politicised. It is the personal choice of that person to do whatever they feel they need to do to feel comfortable in themselves. As a society it is a humanity issue, are you a person that wants to declassify somebody because they are different to you?
'After that... each to their own' - What you may mean is after society has put them through the ringer for feeling 'different', after they have been pushed to change their mind, made to feel like a second class citizen, made to feel like they are just 'going through a rebellion phase', a bit of angst, then once they have got through that without killing themselves then 'each to their own'.