o2 drug of choice??

followed a thread here into pretty good info about leaky exhausts:
detectors of and the need for same. and, if the detector goes off i
should then....?

also, i've read here about how cool it is to hit the o-bottle at night
and watch the lights get bright.

also, today i was doing my 5th heavy crosswind citabria landing and
dance-of-1-wheel (did one where it was a one wheel landing then 1
wheel all the way down(1500 - 2000 ft.) to takeoff except for one drop
where i thought she wanted it down. shortly thereafter performance
nosedived as i got tired. i think that if i had o2 handy i would have
taken a hit or 2.

whats the deal with o2. it doesn't really seem all that expensive and
it seems like it should be the pilots drug of choice. wrong(again)?

dan