Might want to include context there:

>Of course, I have no real evidence for my views; ... On the other hand, the people who talk about the great difficulty of factoring have equally little evidence.

When we talk about the 'difficulty of factoring' there's an implication. The direct meaning is that there may well be a simple algorithm for factoring that has yet to be discovered. No one disputes this.

The implied idea is that this discovery could happen at any time and all things depending on it are at risk. This is also true but it's unreasonable to think that it is likely given that much effort has been put into this.

Yes we don't know, but two unknowns are not 50:50. Of course regardless of how you estimate its truth consider the cost of being wrong when using anything depending on it.

Whoosh. The point is that NOBODY has any real evidence either way, so one shouldn't have a strong default prior of the problem being truly "hard."