If you (or your SEO team) invest poorly, there’s a good chance that you can hurt your website’s future. We’ve seen scenarios where “experts” rebuilt websites and effectively killed the organic traffic by removing pages and creating extremely slow sites. We’ve seen “experts” buy and sell links from the “open market” and get the websites hit by manual actions from Google.
It might surprise you to find out that the worse thing that can happen isn’t “failing to get results”, it’s a lot worse, you can do damage that’s extremely hard to undo, sometimes even impossible to fix.
Therefore, you need someone that can properly manage your SEO budget and put it to good use. Someone that knows how to grow your website naturally (even if slower at times) and with safe methods that ensure your website’s stability.