As a fellow engineer, I think I've been there myself. What helped me was realizing that I had the wrong mental model of what "launching" means.
Think of product development like farming: we engineer a product (seed), plant it in the field, and then customer attention (water) nourishes it while our customer support (care) nurtures it over time. Eventually, we harvest the results. In this model, it makes sense that we obsess over the quality of our seeds since that largely determines yield when given sufficient water and care.
When you work at a company, you build something, hit a quality bar, and there's a big launch day. But for indie founders, that model doesn't work well. Let me explain why with an expanded version of this farming analogy:
Think of your product as a seed and your marketing as an irrigation system.
Established companies already have deep irrigation channels dug. Water (customer attention) flows naturally to their fields. Thousands of eyeballs naturally see their products every day through existing marketing channels, social media presence, and brand recognition.
The reason your experience at work makes you believe launching is so crucial is because your company has already built these irrigation channels. They've constructed a system that brings fresh eyeballs to look at proposed solutions each and every day. As an engineer there, you're just putting seeds into already-prepared soil. You get everything ready, then turn a valve to divert customer-attention water from another established field to your new ground. Then you watch your product work (or not) for all these customers and grow.
But as a solo founder, you have no irrigation channels yet. There's no natural flow of attention to what you're building. You don't have a marketing channel established. It feels like you have a tiny cup of attention (your personal network), and that's understandably terrifying. If you spend your one cup of attention on your seed and it doesn't grow, you're screwed. You've used up your limited resource with nothing to show for it.
Your fear likely comes from feeling like you have a small, non-renewable supply of attention. Once used up, that's it.
Here's a thought experiment: Imagine I promised to bring two real potential customers to your house every day (let's say I'd pay you $10,000 for each day I failed, so you know I'm serious). Two real human beings, just like the people you validated the idea with. Brand new. Never seen them before, never see them again.
How would you feel about your product then?
If you knew you'd get fresh eyeballs on your product daily - a guaranteed stream of attention from the right people - the pressure of a "perfect launch" would vanish. You'd just explain your solution, get feedback, fix issues, and try again tomorrow with new people.
I personally believe it's impossible for any engineer to fail if they get 100 days of direct feedback from people. Tell me specifically how getting feedback from a different person each day for 100 days won't work.
Concretely, find where your potential customers already hang out online.
Here's what most people here would advise: Finding people ALREADY looking for a solution:
1) Instead of cold DMs, I searched for posts like "anyone know a tool that..." or "frustrated with [competitor]" and offered genuine help.
2) Leading with help, not sales. My first message is usually answering their question thoroughly.
3) Only AFTER providing value did I mention "I actually built a tool that might help..."
My email is in my profile if you want to talk about it further.