The whole point of grid systems is martingale. A grid without matringale is the same as guessing the trend over and over again.
Nobody can foresee the trend direction so everyone is just guessing. But if you guessed it wrong without martingale, then you'll never hit TP or even BE because you didn't raise your lots to counter your wrong guess...and if you close your positions at SL, then you have to guess again and hope for luck just to get back to square one. This is where martingale kicks in. It gives you a second, third..etc chance to hit TP.