There is a huge difference between buying a car and being sold one. You may have had the experience of “car shopping” where a salesperson seems to be able to overcome every objection you have to buying a certain car that they are trying to sell.
Every reason you bring up as to why you aren’t interested in a particular vehicle they have a counter argument to it e.g., you may tell them that it is too expensive and the monthly payments would be too high, and that you don’t want to be paying more than $300 per month.
Their response is to extend the length of the loan from three years to four years in order to bring the monthly amount down etc. In old-fashioned sales talk this is referred to as “closing doors”, with the doors being the various ways you can exit the deal.
Once the cost “door” is closed you have one less way/reason to walk away. Salespeople often rely on “reasonableness” as a means of closing deals with reluctant customers i.e., once a person has had all of their objections dealt with, they feel obliged to buy, because they have no reason not to, even if they simply don’t want to.
Salespeople – the good ones - are usually more skilled than the customer when it comes to closing/leaving open doors to exit through. Predatory individuals use similar methods to salespeople, though they’re not usually as sophisticated in the employment of them. It is also worth noting that not all salespeople sell in this manner.
By this time Mike has employed a variety of tactics to no avail. He’s applied direct pressure (ignoring/discounting your “no”), he’s typecast you (presented you in a light/way that you feel you need to reject), and he’s loan-sharked you i.e., called in a debt.
He’s starting to, other than directly physically forcing his way in, run out of options. If this wasn’t real life and you were watching this interaction unfold as part of a movie, you would know by now that Mike is not a person with good intentions and in some way means to harm, and/or take advantage of the person he is dealing with.
If you then watched/heard him say the line, “Please just let me in. Don’t worry, nothing’s going to happen.”, you might think that the scriptwriter has been a little heavy-handed with the dialogue i.e., it’s obvious that something bad is going to happen.
What Mike is doing here is trying to close a door. By telling you that nothing is going to happen he’s framing things so that your only objection to not letting him in is because you do think/believe that something is going to happen, and most of us are too polite to make such an accusation against a person i.e., to effectively say, the only reason I’m not letting you in is because I think you mean to harm me.
This is referred to as an unsolicited promise, because it was offered rather than asked for. When someone is preemptively answering questions you may have before you ask them, it can be a sign of deception.
If someone is offering a promise or guarantee that they won’t act in a certain way this is also a cause to be extremely suspicious.
There should never be a need for someone to tell you that they are not going to harm you, i.e., that nothing is going to happen, as this should be assumed and doesn’t have to be mentioned explicitly.
It is sometimes worth taking a step back to view yourself, in a detached manner, as an actor in a story/on a stage to evaluate everything that has happened and is happening, rather than just viewing things through your own eyes, and as someone who is emotionally involved e.g., if you were viewing Mike’s interaction with a friend, as a third party looking on rather than as someone directly involved, and you saw him discount her no, typecast and loan shark her and then make an unsolicited promise, you would probably be screaming at her to not let him in.
The unsolicited promise allows a predator to frame your non-acquiescence to their demand/request in a way that makes you look bad, and paints them as the “victim” i.e., you are unfairly and unjustly calling them a threat/danger, whilst making yourself seem suspicious and paranoid etc.
Mike has already told you that other people think about you negatively, and if he retells this story to them, about how you were so overly suspicious of him that you wouldn’t let him into your house to get a book that would really help him out, they are going to think even less of you. Faced with such social pressure(s), and a desire to end this interaction/confrontation, against your better judgment you may decide to let him in.