In terms of your analogy, I think there isn't a spike. Project Fear was warning of knives, rotating blades, boiling oil, demons, and so on - even before the vote was taken. After the result went against their personal preference they've continued to invent other imagined hazards to try to get people to change their minds.
To get back to the real issue, the problem is that the constant moaning by remainers isn't actually preventing the Brexit process - but by dangling the prospect of a non-Brexit in front of the negotiators (on both sides) it is allowing them to be more comfortable with their lack of progress - and this will ultimately benefit no one. It would be much more productive if the people on the losing side of the decision just got on board and helped to make the process as smooth and successful as possible.
Er, the problems with the UK leaving the EU will only happen once the UK has left the EU. All that happens beforehand is that people factor in the likely effects and, say the currency gets devalued, so that inflation rises.
to use the slide analogy, we've been on the slide since March 31, 2017 but the ride is only going to get bumpy after March 31, 2019. Pretending anything else is just silly.
As for the problems ahead:
Do you have any idea how many goods are transported between the UK and the EU? Do you have any idea hoe the UK customs are going to deal with this on April 1st 2019? Do you have any idea what is going to happen with flights to the EU27 on April 1st 2019? Do you have any idea what is going to happen with perishable foods travelling either direction on April 1st 2019?
If you do, please could you inform Theresa May. If you do, can you also explain how these are not going to be disasters?
Pretending that this is the fault of the people who are pointing this out is even sillier.
Pretending that Theresa May has a clear negotiating position is rubbish - she is being ambiguous, because as soon as she is clear on her position she'll lose support. However that is not tenable when we have until March 2019 to finalise everything.
ETA: and I have reported this thread for housekeeping as it's getting long