It's around 1MWh within a fraction of a second.

That means very high peak power, making your whole capture infrastructure extremely expensive, but even capturing 100% of an average lightning bolt is worth <$100 in electricity.

Which is why nobody even attempts this.

yea, i think the low efficiency (plus how to predict where lightning would hit!). Might as well just put up a wind turbine, since wind is much more predictable, not to mention easier to harvest.