As a rule, when somebody thinks it’s a good idea to accept advice from an expert, they are most probably already worried.
[Worry] is the state of being anxious and troubled over actual or potential problems.
Oxford languages dictionary
The problem is, that our clients are more often worried only by symptoms that they can see, rather than by the actual problems that are behind those symptoms, which they often, as they are not really skilled in our craft, frequently misattribute, misjudge or simply fail to notice.
For example, a startup worried about the low amount of cash they still have, rather than being worried about their product’s low profitability, which is causing the cash to run out in the first place.
Your ability to “ground” their worry is one of the most important factors in any client’s perception of your value to them. If you think you are not being taken seriously by a client, or that they can’t tell you apart from amateurs – demonstrate a real reason for them to worry about which they would have missed on their own.
As an expert, it is both your ethical duty and in your commercial interest to make sure that the client is duly worried about the things they really should be concerned about, and to an appropriate degree, so that they can reach a better buying decision. From that point on, the way they talk to you usually changes for the better.