Transitioned vs transitioning

Why is is that people who have fully transitioned seem to look down on and take snide swipes at those that are in the earlier stages of transition and also further down the line?

I see these comments so many times on forums and Facebook pages and I just cannot understand why there is this attitude amongst those that have fully transitioned, they make it and them and us situation. It seems to me that they have lost sight of the journey they themselves made to transition especially the early stages before they were full time in their correct gender and this gives them no right to make the comments they do.

It always causes heated debates when people make these sort of comments and observations on a public forum. For example, many girls were excited about the Sparkle weekend and although this covers people on the whole spectrum of transness, for many pre-transition girls in particular it is their first opportunity to dress fully in the day (and the evening) and go out and about in a fairly 'normal' but safe environment. The excitement of some of these girls sparked many discussions about what clothes and shoes to take and how many! Exciting and scary times with mixed emotions. However the way some post transition girls posted was awful calling these excited girls hobbyists and berating them for taking so many changes of clothes.

Hang on.... I am cis female and I took MORE shoes than Lucy and probably just as many change of clothes as she did; 
1. I had to allow for the very interchangeable and unpredictable English weather, 
2. cater for any accidental spills,
3. allow for different places we may be going to (other than the ball we had nothing actually planned). 
The day of the ball I changed 3 times and 2 of these were in the evening. Does this make me a hobbyist doing exactly the same things as my trans counterparts? And no, I didn't wear them all but had them there just in case.

Does it matter how people choose to dress? This is another thing that was slated. In my cis life I have plenty of very unique and colourful cis friends who dress in a very eclectic manner. Just because someone is transgendered who is it that dictates how they have to dress? Everyone whether trans or not should be able to dress in their own style. In every walk of life there are those that dress flamboyantly and some damn right outrageously but good on them! They are being themselves and not causing any harm to anyone else.

These critical people are supposed to be in the same community and I just cannot understand why they have this sort of attitude. Obviously it is not all people who have fully transitioned that have this attitude however these few are very vocal and just do not understand the damage they are doing to peoples confidence. Lucy and I had a discussion about this situation because of several forum topics she had seen and shared with me and the one thing she is adamant about it she will never forget the journey she is on and will never look down on anyone at an earlier stage than her, even when she has fully transitioned.