The key phrase in your post seemed to me, where you talk about the fear of losing about a large bet amount, if this causes fear, then it would be reasonable to avoid this combination, just do not make large bets that you are afraid of losing....
Yes, that's right, if a big bet makes you afraid, the easiest solution is to reduce the bet to a level that is comfortable for you. And it's even better to make a plan in advance, determine the strategy and betting level and try to strictly adhere to it, then your condition will be completely under control and you will enjoy gambling, while losses will be reduced to a minimum. I have been convinced many times that a pre-planned plan is of great help in gambling.
Yes, it is actually that simple to overcome the problem of fear, as you said that a gambler only needs to lower the amount of their bet according to the amount they are ready to lose, but if for example this action still cannot make them a responsible gambler then of course the only solution is to stop gambling completely, because after all gambling will always be about making risky decisions, not only about winning but also the risk of losing is a part of the game that can never be separated. On the other hand, one of the reasons why lowering the amount of the bet is always recommended is the first so that the amount of our loss is not too large and also so that we do not easily experience emotions, but in the end this is the choice of each gambler but I am sure everyone never likes losing large amounts of money.