2.8 billion is nothing. Damage due to market speculation was (very) short lived and, like, the market always spikes around. A random car bridge somewhere rusting through (thanks to germany hating trains) probanly has more impact in replacement cost and economic downturn than that.
You can't blame the economic trend of a major country on 3 billion €.

but was unlikely to remain off for years as it has

I don't see why. Russia manufactured the original turning off of nordstream 1, they wouldn't have reengaged it until pro russian politicians got to power and deepened the influence by opening ns2. Which based on current trends would have been at minimum till the start of 2025 government change, or more likely still not. And who knows what it'd have done for germanys rising nazi party.

The effects were constrained to a few months, by spring 2023 it was thoroughly patched up. Germany did invest a lot for that, but outside state finances, to the wider economy, leaving russia controlling the market speculation would have been way more damaging for way longer.