All or 99% of profiles you see are tend to be fictional. There are no a real person on the other side, so no one will respond your messages. Once again, all profiles disregarding women age and prettiness are fake.
Any welcome message you get to your inbox is written by a script/bot, so they don't respond. Welcome messages like "Hi!" or "Hi sweetie!" are simple and never get out of context, so you can't suspect scum at start.