Code was fine, the only thing that had to be changed was the position of the break-validation towards the end of the loop and to remove the output message from the break-validation to avoid printing the message twice.

Refactored for-loop:

for (let i = 1; i <= daysOfTrip; i++) {

// if (currentExpenses > budget) {

// console.log(

// `Not enough money to continue the trip. You need ${diff}$ more.`

// );

// break;

// }

let dailyFuel = priceFuelKm * travelledDistanceKmDaily;

currentExpenses += dailyFuel;

if (i % 3 === 0 || i % 5 === 0) {

currentExpenses += currentExpenses * 0.4;

}

if (i % 7 === 0) {

currentExpenses -= currentExpenses / groupPeople;

}

travelledDistanceKmDaily = Number(input.shift());

diff = Math.abs(budget - currentExpenses).toFixed(2);

if (currentExpenses > budget) {

// console.log(

// `Not enough money to continue the trip. You need ${diff}$ more.`

// );

break;

}

}