If your existing website is creating successful outcomes -- that is, it's easy to navigate, effectively communicates what your business does, clearly tells customers why they should choose you and drives conversions -- don't let a web agency convince you to spend the money on a major website redesign.
The Internet is an extremely powerful platform that allows entrepreneurs to reach a worldwide audience. The right concept paired with the right marketing can lead to explosive growth and revenue. When asked about revenue goals, a large majority of startup founders will say, "We want to hit $1 million in revenue."
As an entrepreneur, you're going to make mistakes. Some of those mistakes might work out in your favor. Others might threaten the health of your entire business. Even though it's useless to prevent every mistake (as you'll make some no matter what), preventing the mistakes you can is a wiser strategy.