You might recall, this is the scripture Satan used to test Jesus in the wilderness; to which Jesus replied, "Thou shalt not tempt the Lord thy God" (Matthew 4:7)

It's good advice...don't jump off a bridge to see if the angel's will keep your foot from dashing on the concrete below.  That would be foolish; just as Paul told the disciples that "grace" did not give them liberty to sin more (Romans 6:1)

In the first place, this scripture is preceded by a condition..."He that dwelleth in the secret place of the most High..." (Psalms 91:1)  The "secret" place is the kingdom of God, which is within you (if you are reborn Spiritually)...so it follows that you must be "born again" to have angel's watching over you, right?  Not necessarily.

You must be a child of God (whom he knows from the womb), so even if you're walking in sin, his angels are keeping you safe, until...(however long God gives you to repent and return to him).  I mean, when your kids do bad things, they're still your kids, right?

Are you a child of God living a sinful lifestyle?  If so, he's keeping you safe...giving you time to repent because it is not his wish that any of his kids should perish; but he gave them "freewill" to live whatever lifestyle they wanted...blessed or cursed.

If you're a child of God, angels are watching over you; but there is so much more God has and wants for you...if you will just repent and return to him.

You see, until you're born again...nothing else matters.