What does triathlon share with investment? 

To a certain degree, training for triathlon, can be compared to investing moneTriathlon1Credit: Steven Fruitsmaak at Wikimedia Commonsy in market stock options. When you are at the beginning of a new year, and you face yourself with the idea of how to push the envelope on those savings sitting at your bank account, you will try to find the best investments. Also, you will probably take into account the estimated growth and risk factors each and every investment has, so you can minimize the possibility of losing all your money. Good investors know that the trick is to find balance between those two factors. 

Similarly when talking about triathlon training, as opposed to money (in the case of investment) the commodity or resource you have to look about getting a return on it's time. Time is almost a luxury for many in the competitive ages we live in, so the goal then switches from growth to using wisely the amount of time you have... you must look for ways to obtain a sizable fitness return. 

How can you get a sizable fitness return out of your time asset? 

Most noticeable increase in fitness comes always from high intensity and high volume training sessions.

Great is that the only thing I must worry about?

Special consideration must be taken into account when employing this training method, as the downside or potential pitfalls are also great, if you don't put the right attention and mindset while training you can find yourself either injured, getting a feeling of overtraining (burnout) and illness, this last one due to the body focusing on repairing from each workout resulting in a lack of energy to combat other ailments such as infections.

How can I reduce the risks that pose when training in high workloads? 

First thing you must consider upon asking yourself this question is also some questions:

How fit am I really?
Where does my fitness level stand? 

The key to wise training is to know where you stand on the subject of fitness related to yourself and where are your goals taking you. 

What can I do to establish goals or help improve the ones I already have?

Your goal must be something that can be measured. How will you determine how close are you to reaching it? Getting back to the first idea of this article, anyone involved in finance knows, that to measure his success, he only needs to count how much money he is making out of his investments.
So a measurable goal for triathlon wouldn't be "feel at the top of my game" but it could well be finish the next race below my last race time. 

Aim to keep your goals in some level of your comfort zone, sport psychology studies have shown that very high or low goals end up acting as a deterrent to any sports training.

Last but not least...

As any entrepreneur,  businessman, accountant... would know it's better to focus on a certain volume per operation than to engage in multiple small operations (making the result far more unpredictable) which usually ends up reducing control over the possible outcomes.
Same principle applies to triathlon:

It's better really to focus on volume rather than distance.

When you set your training goals you may want to say to yourself every week I will run 75 km but then what happens if one week you can't run 75 km, you will probably start losing faith since you are already losing grip on your objectives.

If you reexamine this goal, and you try to focus it on volume, the result could then be:

Each day I will train 2 hours. This way if some day it's raining and you find yourself unable to cycle or run you can always walk down to your local pool and train. 
This way your goal, stays flexible enough, to allow room for training adjustments and also keeps your training independent of environmental changes.