If you scroll down to the bottom of your worksheet, you'll see the table. Since
you used a step of 1, it saw the whole table as a giant range (instead of
individual cells). And inserted as many rows as there are rows in your table.
If you want to insert a row between each row (I wouldn't do this), you could use
this (that works from the bottom up):
Option Explicit
Sub testme2()
Dim iCtr As Long
Dim LastRow As Long
Dim myRng As Range
With ActiveSheet
LastRow = .Cells.SpecialCells(xlCellTypeLastCell).Row
Set myRng = Nothing
For iCtr = LastRow To 2 Step -1
.Rows(iCtr).Insert
Next iCtr
End With
End Sub
The reason I wouldn't do this is that those blank rows really mess up things
like autofilter, charts, pivottables.
If you agree (and come to your senses <vbg>), maybe just doubling the rowheight
would be sufficient.
You could use something like:
Option Explicit
Sub testme2A()
Dim iCtr As Long
Dim LastRow As Long
Dim myRng As Range
With ActiveSheet
.UsedRange.Rows.AutoFit
LastRow = .Cells.SpecialCells(xlCellTypeLastCell).Row
Set myRng = Nothing
For iCtr = LastRow To 2 Step -1
.Rows(iCtr).RowHeight = .Rows(iCtr).RowHeight * 2
Next iCtr
End With
End Sub