For me personally, I would just gamble that 1 btc because it's a huge bankroll when it comes to gambling and if you have a huge bankroll you have more chances of winning but if you want a safer play then go for investment.
Probably that depends on the amount of winning your targeted and the type of game you are playing, one can win in gambling if he has a specific plan and will be able to execute it. With 1 BTC if you aim to reach a winning of 100 BTC, that so much luck is needed here. Growing more than 100% of your initial bankroll is already difficult therefore the risk is always there.
Well, getting 100BTC from 1BTC is actually 10000% and honestly... The odds that this happens is really really low and aiming for it it's just a waste of time.
And it is not guaranteed that even you have big bankroll you have a lot of chance of winning, don't forget that you have a lot of chance to lose too and with much bigger money.
Probably with that amount, I will cut it into two shares, half for gambling which is 0.5
BTC and half will be in investment, maybe in bankroll casino's.
So even I will lose that half amount, I still have a hope that I can recover it with my investment even the progress is going to be slow.
Bankroll is not the main key of winning, you win because you can predict more winners than losers, that's it. However, if you are really serious with earning big in gambling, you might want to put big amount so you can also win big amount if you can continue your success while betting small.
It's a difficult job, you need to consider a lot of things including managing your emotion.