Signed a contract that said the job is not guaranteed and could be let go without reason

After I had my interview they made me sign a contract that said I will take my job seriously and do my best and then at the end it said: 'This job is not a guarantee of employment. I understand that my employment could end at any time without warning.' I know that a job isn't forever and it's possible to be let go but to make someone sign a contract and have it in your face that you could be let go at any given time would make someone think that they have one foot out of the door. To me it sounds like they have let go of a lot employees and have people going in and out of the job. Has a job ever had you sign a contract like this? I've worked many jobs and never signed anything close to this.