Life today is based on reading. You should read the Internet, read the news, read emails, etc.. So if you do not read fast enough you will be spending a lot of time reading, so you will not have time for other tasks.
The speed reading is achieved mainly by silencing the subvocalization. Most people read at a speed of 200 to 250 words per minute. If subvocalization is not muted, you can only read the speed you read out loud.
Flash Reading helps you improve fast reading thru several exercises.