How do you write an opening sentence that makes me keep reading the next few sentences, really? Microscopic attention span - that's what will characterize most

How do you write an opening sentence that makes me keep reading the next few sentences, really? Microscopic attention span - that's what will characterize most online readers if you're writing something online. In this context, any thought of "literary value/quality" is useless. As opposed to the OP, most are writing for maybe readers that have not real intention whatsoever to keep on reading. I know people that when they see an email longer than 5 lines of text on their display from someone unknown, they just throw it away without bothering to read it at all! The questions I'd like answered are: - How can you write an opening sentence that the reader's semi-conscious mind decodes even before he decides to keep on reading or not (with a 90% probability of the second outcome), and makes him change his mind and keep reading instead? - Should I just add a "TL;DR" section on top of every long article I write because most people will not read it anyway, and hopefully at least this short message will get across? Or will this be a spoiler and make all readers just scan the "TL;DR" and nobody will read the full article now? - How to prevent the "scan to see how long it is and decide not to read it if its too long regardless of title or content" way of thinking of a larger and larger portion of the population (and not necessarily the most ignorant: a very smart person told me that we won't read something longer than a paragraph because "if you can't summarize it in a couple short sentences, the I'll assume you don't know enough about what you are writing for me to worth investing the time and attention to read it") So then, are we all condemned to write only "elevator pitches"? - Will overdoing it by using interesting "reader engagement tactics" just make the reader believe that I'm actually trying to sell them something and stop reading because of this assumption?