Please help me with this!

I have 3 worksheets with the same format including Customer_ID. Each column has more than 65000 values. I wanna auto copy them all to another sheet including values of three exist worksheets. The values changes every week so I wanna have it done automatically
For example,
A B C
Row 1 1 5 10
Row 2 2 4 15
Row 3 2 3 10

I wanna make a single column
A
1
2
2
5
4
3
10
15
10

Help me please!

Thank you so much.