She's doing it as a strategic move. Labour are in a weak position right now, and since the Tories have been polling well she wants to get the general election out of the way earlier than planned so that she can proceed with her harmful Brexit negotiations with the perceived backing of the public. A month or so ago, the Tories won a constituency in Stoke in a by-election, which is the first gain made by a sitting Government since the 80s. That's obviously emboldened her to change her stance and request a snap election.
Honestly though, many people I know are already saying "we are screwed" - But I'm done rolling over. I'm not accepting this as a given - The Tories need to fucking go. If we've learned anything from the last 18 months, it's that as far as politics are concerned, nothing is sacred anymore. Anything
can change in an instant - And the only thing I know for sure is that the country cannot continue down the path it is currently on. Since 2010, the Tories have generated more new debt than every Labour Government in history, combined. They've run the NHS into the ground, putting it from surplus pre-2010 to £2billion in deficit. They've imposed contracts on junior doctors, offered sweetheart deals for large corporations and pushed a harmful programme of austerity which has gutted vital public services. And perhaps worst of all, they've caved to UKIP pressure to hold a harmful and divisive referendum that has only succeeded in creating instability whilst offering no real benefit.
Now is not the time to be stubborn - We need to elect Jeremy Corbyn. He may not be perfect but he is a genuine left wing candidate.