I don’t understand why my business works or not

As highlighted below it would depend on your source of users or triggers for your user to buy. It is possible that different sources are effective at different times. Other reason could be purchases are based on certain short duration market trends that may be outside of your control and it might be best to only market when those trends are active in order to be effective.

Do instrument; fancy word for add code to understand where users are coming from and how they navigate in your product, your products!

All the best!

Great post. Loved it.

You in fact hold all the power. You just need to understand your customers better.

Others had great points - it's time to start tracking and analysing data. Start by asking basic questions:

• Do you have a steady flow of traffic?
• What is the conversion rate?
• What channels do you use for marketing?
• Who are your customers?
• What are your unique selling propositions?

Then it's time to start experimenting to understand even better:

• Are you targeting the right demographic for your products?
• Do you communicate clearly what the added value of your service is?
• Are the channels you're using effective, or should you pivot?

You can adjust all of these different things and monitor if the performance is getting better or not. There's a lot of variables that are unclear without having context regarding your businesses, but the "issues" (ie. opportunities for you!) could range from lack of clear value proposition, suboptimal website, people simply not knowing about you, your products not offering big enough of a value to the customers, etc.

So long story short - start by asking yourself questions about your business, who you are, what do you offer. Then start measuring the data. Understand the data. Experiment with the data. Rinse and repeat.

Best of luck!

I've experienced this while marketing a product for an F& B company. Our revenue fluctuated to the point where there was a month with no growth (i.e., minus from the previous month). The startegy we used was to focus on retaining customers who had previously purchased from us and testing different offers.

What marketing or sales efforts have you done so far?

Absolutely, Mickael. After over 20 years in business, one clear lesson I've learned is that consumer behavior can be quite irrational. There often aren't discernible trends in how or when people decide to purchase. While you can occasionally spot broader market trends, they don't always explain the day-to-day variability you're experiencing.
What sector are you in?

Try to integrate analytics, monitor them closely. Learn which sources your users are coming from, see what makes them leave, what makes them convert. I'd recommend Microsoft Clarity for this, it's free.