Well with a bigger multi bet.. your odds payment are much bigger... so I bet multiple different selections at the end to cover most of the probable outcomes. I know this will reduce the payout amount, but a win is better than nothing at all....
This strategy did not work very well with the Soccer World Cup, because there were simply too many upsets. I did manage to win some configurations at the end, but that did not make up for all my losses.
And that was to be expected, if the only thing required to become profitable was to do that then casinos would go bankrupt due to their players beating them over and over again with this strategy.
Personally I avoid parlays precisely to avoid the frustration described by the OP, as it can be very exasperating to win several bets in a row and then lose everything because you failed to predict a single outcome accurately, so it is better to take single bets, that way even if you happen to lose once you can still receive the profits from the rest of outcomes you predicted correctly.
I also think that way, that single bets are less risky, but the problem is that in the long run they are not very profitable, let's see that if a person bets on a game with odds of @1.60, and then loses that bet , then goes back to betting on a game with odds of @1.70, loses the bet again, then goes back to betting on a game with odds of @1.80 hits the bet, that person will still be at a loss, will need to hit many games with those odds of @1.80 at least if you want to make some profit
now let's go to the multibet bets that I also consider very risky, if a person makes a multibet bet with a parlay of 3 teams and the odd stays at @4.00 then that person loses a bet, then that bet in another multibet and with odds of @4.00 and loses a bet, but then that person bets on another multibet with an odd of @4.00 and the bet is right, so that person is already in profit and it is enough that the next multibet with an odd of @4.00 is right and there will still be room to place more bets, of course this implies that the person always makes bets with the same amount of money
also the person needs to know well the teams in which he will place in the parlay and never think that he can always win, in games of chance the only way to profit is even making multibet bets and counting on luck in that case, because simple bets, however much the person keeps getting it right, it is enough to have a few losing streaks for the person to be at a loss and everything gets worse because it is very difficult to find games that have good odds, so if the person makes single bets they will have odds of @1.50. or you'll have to go to the BTTS market which has odds of @1.60 and above in most cases, in the over market I don't see very high odds either in most cases. maybe even in the under goals market there is but it is another market that is very difficult to predict