Safari seems to ignore my /etc/hosts file

My /etc/hosts file contains this:

# Host Database

#

# localhost is used to configure the loopback interface

# when the system is booting. Do not change this entry.

##

127.0.0.1 localhost

255.255.255.255 broadcasthost

::1 localhost

fe80::1%lo0 localhost

127.0.0.1 youtube.com

When I run the command traceroute youtube.com I receive the expected results (youtube.com is resolved to 127.0.0.1):

traceroute to youtube.com (127.0.0.1), 64 hops max, 52 byte packets

1 localhost (127.0.0.1) 0.272 ms 0.118 ms 0.063 ms

However, when I type youtube.com in Chrome or Safari, my browser doesn't establish a connection with 127.0.0.1 but instead with another IP address. I would have expected Chrome and Safari to resolve youtube.com to 127.0.0.1.

Why are Safari and Chrome seemingly ignoring my /etc/hosts file?