The problem with your "concise" solution is that it's unclear whether your program matches the problem description. If you don't care about the latter, here's an even more concise one:

use 5.010;
say "Please wait while I run a simulation ....";
sleep 5;
say "Elves have wrapped a billion parcels, calling FedEx ....";
sleep 10;
say "Not switching wins 33.3% of the time";
say "Switching wins 66.7% of the time";
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