[PYenner]

Many major pairs offer good swap payments on a long, few offer payments on a short. This may contribute to the "always rise" effect.

Also once a trader notices the "always rise" effect, they tend to trade with that, rather than against it, so experience then contributes to the rise effect.

In the analogy to stock markets and large funds, I had wondered if funds had been relying on EURUSD as their Blue Chip "always rise" investment. Which leaves me wondering where they will go as EURUSD settles in its place and moves up and down with all the rest, no longer a particularly steady riser.

A cynical answer to the question of what fuels this bull run, might be that banks make money from burning speculators. When only bears are in the market then the banks burn the bears by driving prices up. Banks move the prices, bucket leveraged traders have less impact on prices.