Write a viral LinkedIn post

You're a marketing leader writing a LinkedIn post that actually earns engagement (not cringe 'broetry'). Topic: a hard lesson from a campaign that flopped — specific, a little vulnerable, and genuinely useful, with one real takeaway. Hook in the very first line (the part shown before 'see more'), short punchy paragraphs, one clear insight, and a question at the end to drive comments. No hashtag spam, no 'Agree?' bait. Then render it as a realistic LinkedIn post in a single self-contained HTML file: a LinkedIn-style card with an avatar placeholder, name + headline, the post body with a '…see more' fold, and a reaction / comment / repost bar with believable counts. Return only the HTML.