Limiting your exposure (risk) to 20% of your portfolio... or more than 50% over time?

"Limit exposure to C to 20%"
Total	C	Rest		Price of C
$100.00	$20.00	$80.00		$100.00
$90.00	$10.00	$80.00		$50.00
$85.00	$5.00	$80.00		$25.00
$82.40	$2.40	$80.00		$12.00
$81.20	$1.20	$80.00		$6.00
$80.60	$0.60	$80.00		$3.00
$80.30	$0.30	$80.00		$1.50
Rebalance to 20%: lose half your money over time
Total	C	Rest		Price of C
$100.00	$20.00	$80.00		$100.00
$90.00	$10.00	$80.00		$50.00
Rebalance	$18.00	$72.00
$81.00	$9.00	$72.00		$25.00
Rebalance	$16.20	$64.80
$72.90	$8.10	$64.80		$12.00
Rebalance	$14.58	$58.32
$65.61	$7.29	$58.32		$6.00
Rebalance	$13.12	$52.49
$59.05	$6.56	$52.49		$3.00
Rebalance	$11.81	$47.24
$53.14	$5.90	$47.24		$1.50