Excel – how to connect a graph max with original (0,0) point

I made a three line comparison graph by selecting all of the data as a block i.e. the X axis and the three Y axis data points. I then used the same Insert > Line > 2D line.

The chart popped up as desired.

I don't know if it made a difference but I had the data arranged in columns with headings, i.e.

Column A - X axis
Column B - Data set 1
Column C - Data set 2
Column D - Data set 3

This can be accomplished in Excel, but it's not native and requires a bit of creativity. Here's a brief concept (if you provide more accurate sample data, I can provide you a better description of your specific example):

1. Split your data into two halves, with a common horizontal edge. These can mirror, but don't have to.
2. Adjust your data so that the X Axis is the split.
3. Add your top half data as an Area Chart. This will create the top half of your shape with fill down to the X Axis (light blue in the sample).
4. Add your bottom half data as a second series to your chart. This will create the bottom half of your shape with fill up to the X Axis (light red in the sample).
5. Format the fill so that the colors match, and adjust any other aesthetics you want.
6. Since the shape's X Axis (light gray) may not match your measured values (light blue), you can add a second set of Axis to show your actual values.