It isn't fine for him to keep lying. The media really need to start calling him out on every single lie. They are doing the country a huge disservice not to.
It shows his absolute distain for the electorate. Mirrored, it appears, by the rest of the current Conservative party. (The changing of the twitter name to Fact-check UK for example)
Johnson thinks he's so much cleverer than us that he can lie about the big stuff AND the little, inconsequential stuff, and we will swallow it because we aren't clever enough to unpick it.
Not all politicians lie, some are very hardworking and dedicated. If you think you're being lied to by all of them and that is acceptable, it tells me you are (like Johnson assumes) a lazy thinker, uneducated or entirely complicit in the deceit. There is no such thing as democracy if you think everyone is lying.