I'm the first person who would have a go at someone who i found in my house purely due to how I am, but at the same time I know first hand of a case where that went very wrong.
A friend of the family (my dad's best mate's son, who i've known most of my life), who is a fairly capable bloke when it comes to handling himself, confronted some intruders at his home a couple of years ago. They were there with the sole intent of relieving him of his Impreza WRX STi PPP. He had a baseball bat, there was 3 of them in a confined space with very large knives.
Luckily, his dad lives accross the road and heard the commotion and the car being driven off. He was found next to his bed bleeding to death, with a trail of blood up the stairs where they'd dragged him upstairs making him tell them where the keys were. He'd tried to be the hard man even once confronted with a knife. He'd left the keys in his bed side cabinet so that thieves couldn't find them easily, and it nearly cost him his life. Lucky for him, his wife and young son was at his wife's parents house for the night for one reason or another.
Since then, his keys are left plainly in sight once you get into the house.