The Oil Drum

Most (all?) helium is extracted from natural gas wells where it is a dilutant that lowers the heating value of the gas.  While helium is almost never enough on its own to make the untreated gas non-commercial (max 7% or so, usually 1% or less), there are usually co-mingled non-combustibles like nitrogen that are also present. Nitrogen is expensive to remove and is seldom done unless there is a lot of gas to amortize the big cyrogenic plants required.

The bottom line is that helium is often from non-commercial-grade gas resources that can't be sold and won't burn.  They are two different markets.