The only reason Labbour and Corbyn are happy about election is expectations. They were expecting to lose by a massive margin and didn't. That tells a story . Any organisation with that mentality never wins anything.
Have you ever seen Lewis Hamilton or MUFC or Murray happy at not winning. Only loosers rejoice at not loosing badly.
That mentality must change in labour.
And only idiots rejoice if they win an election only to face long term damage when they prove unable to undo the damage caused by a combination of foolish voters opting for Brexit and the stupid Tories for setting the whole fiasco in motion in an attempt to sort out internal party conflicts.
The Tory party made the mess, let them take the flak when they cant put it right again.
The Labour Party won because the Tory party has undermined itself very badly and the EU will take advantage of that.
So a hard damaging Brexit is no longer an option
If the Tories had gained a big majority the EU would have known the country was behind them, now they know that isn't the case, and May and co really can't threaten them with a walk out any more.
Your view of Politics is far too simplistic.