I think this is a safe script because it uses several chance.
Based on my experience, playing with one chance for a long time is very rare to get profit because usually the longer we play, we will get a long red (even very long)

IF YOU PLAY WITH BALANCE > 15K DOGE!
to be more secure, change maxbet and multipliers on chance 48 to
multyplier = 2.10945
maxbet = 19

Previous:

    if chance < 60 and chance > 40  then
        if win then
            chance     = 48
            multyplier = 2.1107  =====> to 2.10945
            maxbet     = 17      =====> to 19
            nextbet    = (balance/multyplier^maxbet)*(multyplier-1.00001)
            if previousbet > (balance/multyplier^12)*(multyplier-1.00001) then  =====> to 14
                chance = 90
            end

Becomes :

    if chance < 60 and chance > 40  then
        if win then
            chance     = 48
            multyplier = 2.10945
            maxbet     = 19
            nextbet    = (balance/multyplier^maxbet)*(multyplier-1.00001)
            if previousbet > (balance/multyplier^14)*(multyplier-1.00001) then
                chance = 90
            end

Also change this section

         if lastBet.Chance <60 and lastBet.Chance> 40 then
             if previousbet> (balance / multyplier ^ 12) * (multyplier-1.00001) then   =====> to 14
                 chance = 90
             end
         end
     end

Becomes :

         if lastBet.Chance <60 and lastBet.Chance> 40 then
             if previousbet> (balance / multyplier ^ 14) * (multyplier-1.00001) then
                 chance = 90
             end
         end
     end


If you like this script and make a profit, you can donate a small portion of your profits to the following address

BTC  = 1GvsYC6yHA1Gm6JWfo7KM2oujcfCEE4G5k
Doge = D5VPCkaEa36b7jLdShdQoht2J3Um5jK77E
Ltc  = Li8JY3gigEYSDpun2EYvMfwjS4Ck2iP53f
Eth  = 0x034cc2be76b110b192c45367cb7e1ac36d864455



--Seuntjies Note. Learn to use the Modulo operator, you have SO much unnecessary code!