The expensive mistakes we see are rarely about a bad technology choice. They come from building a product that can't answer a simple question: what happened to this one customer's payment last Tuesday?
Teams spend months on features and nothing on the boring record of what the system actually did, and then every support question turns into an engineer digging through logs for an hour.
If a customer asked you today about a charge from last month, explaining it would probably take someone on your side a while.