Some people just seem to have a lot of luck when they are gambling and can make a lot of money from it, others do not and it can seem impossible to know why. It really depends on what type of gambling they are doing.
If they are playing the lottery or bingo, then there is no skill. However, you may find that people who win more often will spend more money. The more you pay out, the higher your chance of winning something. The more turns that you have will also increase your chances of winning.
Most games have some element of skill in them though. These will partly be determined by the same rule as above, with you increasing your chances of winning by playing more often. However, if you know how to play well, you will increase your chances of doing well.
It is therefore wise to practice playing the games and this will help you to learn the tactics that you will need to win. You can play for free on some websites, which could help you or you could play with friends and not gamble money. This could give you the practice that you need without costing you anything.
There are also many websites and books that will tell you how to get better at certain games. They offer hints and tips and even sometimes strategies which should help you to improve the way that you play and win more games. It is basically all about research and practice and then you will get better at the games that you play. To actually get better at gambling, will also mean that you will need to place bets effectively, making sure that you get the risk level just right to give yourself the best chance of winning the prize that you want.