I do not understand your first sentence. Does it mean you agree we will be poorer?(You used a double negative)I have not said we will not be poorer but question the qualification of your assertion. Osborne predicted mass unemployment and the need for an emergency budget once the result for Brexit was known. The governor of the bank of England has already apologised for his incorrect 'assertion' I would accept slightly lower growth for a few years to gain the benefits.
France's growth was half the UKs in the second quarter, is this the golden club we will be missing?
We could argue at length about whether Osborne or the Bank of England made accurate forecasts when it was generally accepted that there was a "project fear". (Even so those predictions were really talking about post brexit UK not post referendum UK but that has been forgotten).
The issue is what forecast say now - in the cool light of day, with more data than we had in 2016 and without the distortions of an "election" to cloud matters.
If you do agree that we will be poorer then you sit alongside the vast majority of people who think that.